编译原理之语法分析（自顶向下递归下降法 Pl/0语言文法打印语法树）

喜欢ヅ旅行 2022-04-13 07:58 240阅读 0赞

先调用词法分析程序后将单词保存到一个全局的字符串数组result中，并声明全局int变量ip，指向当前的单词下标，然后调用程序函数，即可完成一步步的递归，最后分析出能否规约为一颗语法树。

下面的代码是语法分析部分：

/函数声明
    void subProgram();
    void conExplain();
    void varExplain();
    void processExplain();
    void constDef();
    void statement();
    void varExplain();
    void id();
    void unsInt();
    void dig();
    void processHead();
    void AssignmentStatement();
    void expression();
    void CompoundStatement();
    void conditions();
    void AddAndSubtract();
    void item();
    void factor();
    void MULAndDIV();
    void ConditionStatement();
    void relationship();
    void processCall();
    void readStatement();
    void dowhile();
    void writeStatement();
    
    void  program()//程序
    {
    	ip = 0;
    	subProgram();
    	
    	if (result[ip] == ".")
    	{
    		ip++;
    		cout << "成功";
    	}
    	else
    		exit(0);
    }
    
    void subProgram()//分程序
    {
    	
    	//常量说明部分
    	if (result[ip] == "const")
    	{
    		conExplain();
    	}
    	//变量说明部分
    	if (result[ip] == "var")
    	{
    		varExplain();
    	}
    	//过程说明部分
    	if (result[ip] == "procedure")
    	{
    		processExplain();
    	}
    	statement();//语句
    }
    void conExplain()//常量说明部分
    {
    	if (result[ip] == "const")
    	{
    		ip++;
    		constDef();
    		while (result[ip] == "，")
    		{
    			ip++;
    			constDef();
    		}
    		if (result[ip] == ";")
    		{
    			ip++;
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void varExplain()//变量说明语句
    {
    	if (result[ip] == "var")
    	{
    		ip++;
    		id();
    		while (result[ip] == ",")
    		{
    			ip++;
    			id();
    		}
    	
    	   if (result[ip] == ";")
    		   ip++;
    	   else
    		   exit(0);
    	}
    	else
    		exit(0);
    }
    void processExplain()//过程说明部分
    {
    	processHead();
    	subProgram();
    	if (result[ip] == ";")
    	{
    		ip++;
    		while (result[ip]=="procedure")
    		{
    			
    			processExplain();
    		}
    	}
    	    else
    			exit(0);
    }
    void statement()//语句
    {
    	if (isexists(result[ip]))//赋值语句
    		AssignmentStatement();
    	else if (result[ip] == "if")//条件语句
    		ConditionStatement();
    	else if (result[ip] == "while")//当型循环
    		dowhile();
    	else if (result[ip] == "call")//过程调用
    		processCall();
    	else if (result[ip] == "read")//读语句
    		readStatement();
    	else if (result[ip] == "write")//写语句
    		writeStatement();
    	else if (result[ip] == "begin")//复合语句
    		CompoundStatement();
    	
    }
    void constDef()//常量定义
    {
    	id();
    	if (result[ip] == "=")
    	{
    		ip++;
    		unsInt();
    	}
    	else
    		exit(0);
    }
    
    void id()//标识符
    {
    	if (isexists(result[ip]))
    		ip++;
    	else
    		exit(0);
    }
    void unsInt()//无符号整数
    {
    	if (isexistc(result[ip]))
    		ip++;
    	else
    		exit(0);
    }
    
    void dig()//数字
    {
    	if (result[ip].at(0) <= 57 && result[ip].at(0) >= 48)
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void processHead()//过程首部
    {
    	if (result[ip] == "procedure")
    	{
    		ip++;
    		id();
    		if (result[ip] == ";")
    			ip++;
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void AssignmentStatement()//赋值语句
    {
    	id();
    	if (result[ip] == ":=")
    	{
    		ip++;
    		expression();
    	}
    	else
    		exit(0);
    }
    void expression()//表达式
    {
    	if (result[ip] == "+" || result[ip] == "-")
    	{
    		ip++;
    	}
    	item();
    	while (result[ip] == "+" || result[ip] == "-")
    	{
    		AddAndSubtract();
    		item();
    	}
    	
    }
    void CompoundStatement()//复合语句
    {
    	if (result[ip] == "begin")
    	{
    		ip++;
    		statement();
    		while (result[ip] == ";")
    		{
    			ip++;
    			statement();
    
    		}
    		if (result[ip] == "end")
    		{
    			ip++;
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    
    }
    void conditions()//条件
    { 
    	
    	 if (result[ip] == "odd")
    	{       
                    ip++;
    		expression();
    	}
    	 else 
    	{
    		expression();
    		relationship();
    		expression();
    	}
    }
    void item()//项
    {
    	factor();
    	while (result[ip]=="*"|| result[ip] == "/")
    	{
    		MULAndDIV();
    		factor();
    	}
    }
    void factor()//因子
    {
    	if ((result[ip].at(0) <= 122 && result[ip].at(0) >= 97))
    	{
    		id();
    	}
    	else if ((result[ip].at(0) <= 57 && result[ip].at(0) >= 48))
    	{
    
    		unsInt();
    	}
    	else if ((result[ip] == "("))
    	{
    
    		expression();
    		if (result[ip] == ")")
    			ip++;
    		else
    			exit(0);
     	}
    	else
    		exit(0);
    
    }
    void AddAndSubtract()//加减运算符
    {
    	if (result[ip] == "+" || result[ip] == "-")
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void MULAndDIV()//乘除运算符
    {
    	if (result[ip] == "*" || result[ip] == "/")
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void relationship()//关系运算符
    {
    	if (result[ip] == "=" || result[ip] == "#"||result[ip]=="<"|| result[ip] == "<="||result[ip] == ">"
    		||result[ip] == ">=")
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void ConditionStatement()//条件语句
    {
    	if (result[ip] == "if")
    	{
    		ip++;
    		conditions();
    		if (result[ip] == "then")
    		{
    			ip++;
    			statement();
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void processCall()//过程调用语句
    {
    	if (result[ip] == "call")
    	{
    		ip++;
    		id();
    	}
    	else
    		exit(0);
    }
    void dowhile()//当型循环
    {
    	if (result[ip] == "while")
    	{
    		ip++;
    		conditions();
    		if (result[ip] == "do")
    		{
    			ip++;
    			statement();
    		}
    		else
    			success = 0;
    	}
    	else
    		exit(0);
    }
    void readStatement()//读语句
    {
    	if (result[ip] == "read")
    	{
    		ip++;
    		if (result[ip] == "(")
    		{
    			ip++;
    			id();
    			while (result[ip] == ",")
    			{
    				ip++;
    				id();
    
    			}
    			if (result[ip] == ")")
    				ip++;
    			else
    				exit(0);
    
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void writeStatement()//写语句
    {
    
    	if (result[ip] == "write")
    	{
    		ip++;
    		if (result[ip] == "(")
    		{
    			ip++;
    			expression();
    			while (result[ip] == ",")
    			{
    				ip++;
    				expression();
    
    			}
    			if (result[ip] == ")")
    				ip++;
    			else
    				exit(0);
    
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }

这里是完整的词法分析加语法分析：

#pragma once
    #include<iostream>
    #include<string>
    #include <fstream>
    #include <sstream>
    #include<Windows.h>
    bool success = 1;
    using namespace std;
    char ch;//字符变量，存放最新读进的源程序字符
    char strToken[100];//字符数组，存放构成单词符号的字符串
    int len = 0;//记录字符串的长度
    string klabel[29] = { "+","-","*","/","=","#","<","<=",">",">=",",",";",":=","(",")",".","const","var","procedure","begin","end","odd","if","then","call"
    ,"while","do","read","write" };
    string slabel[100] = {};
    string  clabel[100] = {};
    string  result[100] = {};
    int ip = 0;
    int slen = 0;//标识符表的下标
    int clen = 0;//常量表的下标
    			 //判断是否为数字
    const char *input;
    int index = 0;
    bool isDigit()
    {
    	if (ch < 58 && ch >= 48)
    		return true;
    	else
    		return false;
    }
    //判断是否为小写字母
    bool issLetter()
    {
    	if (ch <= 122 && ch >= 97)
    		return true;
    	else
    		return false;
    }
    bool isDigit(char ch1)
    {
    	if (ch1 < 58 && ch1 >= 48)
    		return true;
    	else
    		return false;
    }
    
    //判断是否为小写字母
    bool issLetter(char ch1)
    {
    	if (ch1 <= 122 && ch1 >= 97)
    		return true;
    	else
    		return false;
    }
    //判断是否为大写字母
    bool islLetter()
    {
    	if (ch <= 90 && ch >= 65)
    		return true;
    	else
    		return false;
    }
    //将下一输入字符读到ch中
    void GetChar()
    {
    	ch = input[index];
    	index++;
    
    }
    //判断ch中是否是空白，若是，则调用GetChar直至读入下一个非空白的字符
    void GetBC()
    {
    	while (ch == 32)
    		GetChar();
    }
    //将ch中的字符连接到strToken之后
    void concat()
    {
    	strToken[len] = ch;
    	len++;
    }
    //对strToken中的字符串查找保留字表，若他是一个保留字则返回则返回他的编码，否则返回0值
    int Reserve()
    {
    
    	for (int i = 0; i < 29; i++)
    	{
    		/*const char *p = klabel[i].data();
    		if (strcmp(p,strToken)==0)
    		{
    		return i;
    		}*/
    		if (klabel[i] == strToken)
    			return i;
    	}
    	return -1;
    }
    //将搜索指示器回调一个字符位置
    void Retract()
    {
    	index--;
    	ch = 32;
    }
    //将strToken中的标识符插入到符号表
    int insertId()
    {
    	slabel[slen] = strToken;
    	slen++;
    	return slen - 1;
    }
    //将strToken中的常数插入到常数表
    int insertConst()
    {
    	clabel[clen] = strToken;
    	clen++;
    	return clen - 1;
    }
    string readFileIntoString(char * filename)
    {
    	ifstream ifile(filename);
    	//将文件读入到ostringstream对象buf中
    	ostringstream buf;
    	char ch;
    	while (buf&&ifile.get(ch))
    		buf.put(ch);
    	//返回与流对象buf关联的字符串
    	return buf.str();
    }
    //检测是否已经存在此标识符
    int isexists(string str)
    {
    	for (int i = 0; i < slen; i++)
    		if (str == slabel[i])
    			return 1;
    
    	return 0;
    }
    //检测是否已经存在此常量
    int  isexistc(string con)
    {
    	for (int i = 0; i < clen; i++)
    		if (con == clabel[i])
    			return 1;
    	return -1;
    }
    int isexists()
    {
    	for (int i = 0; i < slen; i++)
    		if (strToken == slabel[i])
    			return i;
    
    	return -1;
    }
    //检测是否已经存在此常量
    int  isexistc()
    {
    	for (int i = 0; i < clen; i++)
    		if (strToken == clabel[i])
    			return i;
    	return -1;
    }
    //名字表的结构体
    struct symbel
    {
    	string name;
    	string kind;
    	int level;
    	int addr;
    	int value;
    }symlabel;
    //判断是否退出
    
    //主程序
    void lex(string file1)
    {
    	int code, value, num = 0;
    	/*cout << "请输入单词长度"<<endl;
    	cin >> num;
    	cout << "请输入单词："<<endl;
    	cin >> input;*/
    	//char filename[] = "test.txt";
    	//const char *file = readFileIntoString(filename).data();
    	std::ifstream in(file1);
    	std::ostringstream tmp;
    	tmp << in.rdbuf();
    	std::string str = tmp.str();
    	cout << str << endl;
    	for (int i = 0; i < str.length(); i++)//如果输入中有大写字母，则转换为小写字母
    		if (str.at(i) <= 90 && str.at(i) >= 65)
    			str.at(i) = str.at(i) + 32;
    	const char *file = str.data();
    	input = file;
    
    	while (input[index] != 0)
    	{
    		len = 0;
    		//strcpy(strToken,"");
    		memset(strToken, 0, sizeof(strToken));
    		//cout << strToken << endl;
    		//Sleep(1000);
    		GetChar();
    		GetBC();
    		if (issLetter())//判断是否是字母
    		{
    			while (issLetter() || isDigit())
    			{
    				concat();
    				GetChar();
    			}
    			Retract();
    			result[ip] = strToken;
    			ip++;
    			code = Reserve();
    			if (code == -1)//不在关键字表里，即为标识符
    			{
    				
    				int index1 = isexists();//检测此标识符是否存在
    				if (index1 != -1)
    					cout << "(" << strToken << ",id," << index1 << ")" << endl;
    				else
    				{
    					value = insertId();
    					cout << "(" << strToken << ",id," << value << ")" << endl;//输出标识符的三元组
    
    				}//cout << strToken<<endl;
    			}
    			else
    			{
    				cout << "(" << klabel[code] << "," << klabel[code] << ",-)" << endl;//输出关键字的二元组
    			}
    		}
    		else if (isDigit())//如果是数字，即为常量
    		{
    			while (isDigit())
    			{
    				concat();
    				GetChar();
    			}
    			Retract();
    			result[ip] = strToken;
    			ip++;
    			int index2 = isexistc();
    			if (index2 != -1)
    				cout << "(" << strToken << ",int," << index2 << ")" << endl;
    			else
    			{
    				value = insertConst();
    				cout << "(" << strToken << ",int," << value << ")" << endl;
    			}
    		}
    		/*else if (islLetter())
    		{
    		while(islLetter())
    		{
    		concat();
    		GetChar();
    		}
    		Retract();
    		code = Reserve();
    		if (code == -1)
    		cout << "拼写错误"<<endl;
    		else
    		cout << "(" << code << ",-)" << endl;//输出关键字的二元组
    		}*/
    		else//其余情况
    		{
    			switch (ch)
    			{
    			case '+':
    				cout << "(+,+," << "-)" << endl;
    				result[ip] = "+";
    				ip++;
    				break;
    			case '-':
    				cout << "(-,-," << "-)" << endl;
    				result[ip] = "-";
    				ip++;
    				break;
    			case '*':
    				cout << "(*,*," << "-)" << endl;
    				result[ip] = "*";
    				ip++;
    				break;
    			case '/':
    				cout << "(/,/," << "-)" << endl;
    				result[ip] = "/";
    				ip++;
    				break;
    			case '=':
    				cout << "(=,=," << "-)" << endl;
    				result[ip] = "=";
    				ip++;
    				break;
    			case '#':
    				cout << "(#,#," << "-)" << endl;
    				result[ip] = "#";
    				ip++;
    				break;
    			case '<':
    				GetChar();
    				if (ch == '=')
    				{
    					cout << "(<=,<=," << "-)" << endl;
    					result[ip] = "<=";
    					ip++;
    				}
    				else
    				{
    					Retract();
    					cout << "(<,<," << "-)" << endl;
    					result[ip] = "<";
    					ip++;
    				}
    				break;
    			case '>':
    				GetChar();
    				if (ch == '=')
    				{
    					cout << "(>=,>=," << "-)" << endl;
    					result[ip] = ">=";
    					ip++;
    				}
    				else
    				{
    					Retract();
    					cout << "(>,>," << "-)" << endl;
    					result[ip] = ">";
    					ip++;
    				}
    				break;
    			case ',':
    				cout << "(,,,," << "-)" << endl;
    				result[ip] = ",";
    				ip++;
    				break;
    			case ';':
    				cout << "(;,;," << "-)" << endl;
    				result[ip] = ";";
    				ip++;
    				break;
    			case ':':
    				GetChar();
    				if (ch == '=')
    				{
    					cout << "(:=,:=," << "-)" << endl;
    					result[ip] = ":=";
    					ip++;
    				}
    				else
    				{
    					Retract();
    					cout << "(:,:," << "-)" << endl;
    					result[ip] = ":";
    					ip++;
    				}
    				break;
    			case '(':
    				cout << "((,(," << "-)" << endl;
    				result[ip] = "(";
    				ip++;
    				break;
    			case ')':
    				cout << "(),)," << "-)" << endl;
    				result[ip] = ")";
    				ip++;
    				break;
    			case '.':
    				cout << "(.,.," << "-)" << endl;
    				result[ip] = ".";
    				ip++;
    				break;
    			case 10://排除掉换行符
    				break;
    			default:
    				cout << "拼写错误:" << ch << endl;
    				break;
    			}
    		}
    	}
    }
    //函数声明
    void subProgram();
    void conExplain();
    void varExplain();
    void processExplain();
    void constDef();
    void statement();
    void varExplain();
    void id();
    void unsInt();
    void dig();
    void processHead();
    void AssignmentStatement();
    void expression();
    void CompoundStatement();
    void conditions();
    void AddAndSubtract();
    void item();
    void factor();
    void MULAndDIV();
    void ConditionStatement();
    void relationship();
    void processCall();
    void readStatement();
    void dowhile();
    void writeStatement();
    
    void  program()//程序
    {
    	ip = 0;
    	subProgram();
    	
    	if (result[ip] == ".")
    	{
    		ip++;
    		cout << "成功";
    	}
    	else
    		exit(0);
    }
    
    void subProgram()//分程序
    {
    	
    	//常量说明部分
    	if (result[ip] == "const")
    	{
    		conExplain();
    	}
    	//变量说明部分
    	if (result[ip] == "var")
    	{
    		varExplain();
    	}
    	//过程说明部分
    	if (result[ip] == "procedure")
    	{
    		processExplain();
    	}
    	statement();//语句
    }
    void conExplain()//常量说明部分
    {
    	if (result[ip] == "const")
    	{
    		ip++;
    		constDef();
    		while (result[ip] == "，")
    		{
    			ip++;
    			constDef();
    		}
    		if (result[ip] == ";")
    		{
    			ip++;
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void varExplain()//变量说明语句
    {
    	if (result[ip] == "var")
    	{
    		ip++;
    		id();
    		while (result[ip] == ",")
    		{
    			ip++;
    			id();
    		}
    	
    	   if (result[ip] == ";")
    		   ip++;
    	   else
    		   exit(0);
    	}
    	else
    		exit(0);
    }
    void processExplain()//过程说明部分
    {
    	processHead();
    	subProgram();
    	if (result[ip] == ";")
    	{
    		ip++;
    		while (result[ip]=="procedure")
    		{
    			
    			processExplain();
    		}
    	}
    	    else
    			exit(0);
    }
    void statement()//语句
    {
    	if (isexists(result[ip]))//赋值语句
    		AssignmentStatement();
    	else if (result[ip] == "if")//条件语句
    		ConditionStatement();
    	else if (result[ip] == "while")//当型循环
    		dowhile();
    	else if (result[ip] == "call")//过程调用
    		processCall();
    	else if (result[ip] == "read")//读语句
    		readStatement();
    	else if (result[ip] == "write")//写语句
    		writeStatement();
    	else if (result[ip] == "begin")//复合语句
    		CompoundStatement();
    	
    }
    void constDef()//常量定义
    {
    	id();
    	if (result[ip] == "=")
    	{
    		ip++;
    		unsInt();
    	}
    	else
    		exit(0);
    }
    
    void id()//标识符
    {
    	if (isexists(result[ip]))
    		ip++;
    	else
    		exit(0);
    }
    void unsInt()//无符号整数
    {
    	if (isexistc(result[ip]))
    		ip++;
    	else
    		exit(0);
    }
    
    void dig()//数字
    {
    	if (result[ip].at(0) <= 57 && result[ip].at(0) >= 48)
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void processHead()//过程首部
    {
    	if (result[ip] == "procedure")
    	{
    		ip++;
    		id();
    		if (result[ip] == ";")
    			ip++;
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void AssignmentStatement()//赋值语句
    {
    	id();
    	if (result[ip] == ":=")
    	{
    		ip++;
    		expression();
    	}
    	else
    		exit(0);
    }
    void expression()//表达式
    {
    	if (result[ip] == "+" || result[ip] == "-")
    	{
    		ip++;
    	}
    	item();
    	while (result[ip] == "+" || result[ip] == "-")
    	{
    		AddAndSubtract();
    		item();
    	}
    	
    }
    void CompoundStatement()//复合语句
    {
    	if (result[ip] == "begin")
    	{
    		ip++;
    		statement();
    		while (result[ip] == ";")
    		{
    			ip++;
    			statement();
    
    		}
    		if (result[ip] == "end")
    		{
    			ip++;
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    
    }
    void conditions()//条件
    { 
    	
    	 if (result[ip] == "odd")
    	{
    		expression();
    	}
    	 else 
    	{
    		expression();
    		relationship();
    		expression();
    	}
    }
    void item()//项
    {
    	factor();
    	while (result[ip]=="*"|| result[ip] == "/")
    	{
    		MULAndDIV();
    		factor();
    	}
    }
    void factor()//因子
    {
    	if ((result[ip].at(0) <= 122 && result[ip].at(0) >= 97))
    	{
    		id();
    	}
    	else if ((result[ip].at(0) <= 57 && result[ip].at(0) >= 48))
    	{
    
    		unsInt();
    	}
    	else if ((result[ip] == "("))
    	{
    
    		expression();
    		if (result[ip] == ")")
    			ip++;
    		else
    			exit(0);
     	}
    	else
    		exit(0);
    
    }
    void AddAndSubtract()//加减运算符
    {
    	if (result[ip] == "+" || result[ip] == "-")
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void MULAndDIV()//乘除运算符
    {
    	if (result[ip] == "*" || result[ip] == "/")
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void relationship()//关系运算符
    {
    	if (result[ip] == "=" || result[ip] == "#"||result[ip]=="<"|| result[ip] == "<="||result[ip] == ">"
    		||result[ip] == ">=")
    	{
    		ip++;
    	}
    	else
    		exit(0);
    }
    void ConditionStatement()//条件语句
    {
    	if (result[ip] == "if")
    	{
    		ip++;
    		conditions();
    		if (result[ip] == "then")
    		{
    			ip++;
    			statement();
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void processCall()//过程调用语句
    {
    	if (result[ip] == "call")
    	{
    		ip++;
    		id();
    	}
    	else
    		exit(0);
    }
    void dowhile()//当型循环
    {
    	if (result[ip] == "while")
    	{
    		ip++;
    		conditions();
    		if (result[ip] == "do")
    		{
    			ip++;
    			statement();
    		}
    		else
    			success = 0;
    	}
    	else
    		exit(0);
    }
    void readStatement()//读语句
    {
    	if (result[ip] == "read")
    	{
    		ip++;
    		if (result[ip] == "(")
    		{
    			ip++;
    			id();
    			while (result[ip] == ",")
    			{
    				ip++;
    				id();
    
    			}
    			if (result[ip] == ")")
    				ip++;
    			else
    				exit(0);
    
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void writeStatement()//写语句
    {
    
    	if (result[ip] == "write")
    	{
    		ip++;
    		if (result[ip] == "(")
    		{
    			ip++;
    			expression();
    			while (result[ip] == ",")
    			{
    				ip++;
    				expression();
    
    			}
    			if (result[ip] == ")")
    				ip++;
    			else
    				exit(0);
    
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }

这是cpp：

#include"recursion.h"
    using namespace std;
    //主程序
    int main()
    {
    	lex("test.txt");
    	for (int i = 0; i < 100; i++)
    		cout << result[i] << " ";
    	cout << endl;
    	for (int i = 0; i < 100; i++)
    		cout << slabel[i] << " ";
    	cout << endl;
    	for (int i = 0; i < 100; i++)
    		cout << clabel[i] << " ";
    	cout << endl;
    	program();
    	system("pause");
    	return 0;
    }

树的节点的结构和打印的函数部分：

#pragma once
    #include <iostream>
    #include <string>
    using namespace std;
    template <class T>
    struct treeNode
    {
    	int childNum;
    	T element;
    	treeNode<T> *child[20];
    	treeNode(int number, T ele) 
    	{ 
    		childNum = number; 
    	    element = ele;
    		
    		for (int i = 0; i < 20; i++)
    			child[i] = NULL;
    	}
    	treeNode(T ele) 
    	{ 
    		element = ele; 
    		childNum = 20;
    		for (int i = 0; i < 20; i++)
    			child[i] = NULL;
    	}
    };
    template <class T>
    void print(treeNode<T> *root,int blk)
    {
    	treeNode<T> *t = root;
    	
    	if (t != NULL)
    	{
    		for (int i = 0; i<blk; i++)
    		cout<<"|  ";//缩进
    		cout <<"|--"<<t->element<<endl;
    		for (int i = 0; i <20; i++)
    		{
    			print(t->child[i],blk+1);
    		}
    	}
    }

能打印语法树的完整的代码：

#pragma once
    #include<iostream>
    #include<string>
    #include <fstream>
    #include <sstream>
    #include<Windows.h>
    #include "tree.h"
    bool success = 1;
    using namespace std;
    char ch;//字符变量，存放最新读进的源程序字符
    char strToken[100];//字符数组，存放构成单词符号的字符串
    int len = 0;//记录字符串的长度
    string klabel[29] = { "+","-","*","/","=","#","<","<=",">",">=",",",";",":=","(",")",".","const","var","procedure","begin","end","odd","if","then","call"
    ,"while","do","read","write" };
    string slabel[100] = {};
    string  clabel[100] = {};
    string  result[1000] = {};
    int ip = 0;
    int slen = 0;//标识符表的下标
    int clen = 0;//常量表的下标
    			 //判断是否为数字
    const char *input;
    int index = 0;
    bool isDigit()
    {
    	if (ch < 58 && ch >= 48)
    		return true;
    	else
    		return false;
    }
    //判断是否为小写字母
    bool issLetter()
    {
    	if (ch <= 122 && ch >= 97)
    		return true;
    	else
    		return false;
    }
    bool isDigit(char ch1)
    {
    	if (ch1 < 58 && ch1 >= 48)
    		return true;
    	else
    		return false;
    }
    
    //判断是否为小写字母
    bool issLetter(char ch1)
    {
    	if (ch1 <= 122 && ch1 >= 97)
    		return true;
    	else
    		return false;
    }
    //判断是否为大写字母
    bool islLetter()
    {
    	if (ch <= 90 && ch >= 65)
    		return true;
    	else
    		return false;
    }
    //将下一输入字符读到ch中
    void GetChar()
    {
    	ch = input[index];
    	index++;
    
    }
    //判断ch中是否是空白，若是，则调用GetChar直至读入下一个非空白的字符
    void GetBC()
    {
    	while (ch == 32)
    		GetChar();
    }
    //将ch中的字符连接到strToken之后
    void concat()
    {
    	strToken[len] = ch;
    	len++;
    }
    //对strToken中的字符串查找保留字表，若他是一个保留字则返回则返回他的编码，否则返回0值
    int Reserve()
    {
    
    	for (int i = 0; i < 29; i++)
    	{
    		/*const char *p = klabel[i].data();
    		if (strcmp(p,strToken)==0)
    		{
    		return i;
    		}*/
    		if (klabel[i] == strToken)
    			return i;
    	}
    	return -1;
    }
    //将搜索指示器回调一个字符位置
    void Retract()
    {
    	index--;
    	ch = 32;
    }
    //将strToken中的标识符插入到符号表
    int insertId()
    {
    	slabel[slen] = strToken;
    	slen++;
    	return slen - 1;
    }
    //将strToken中的常数插入到常数表
    int insertConst()
    {
    	clabel[clen] = strToken;
    	clen++;
    	return clen - 1;
    }
    string readFileIntoString(char * filename)
    {
    	ifstream ifile(filename);
    	//将文件读入到ostringstream对象buf中
    	ostringstream buf;
    	char ch;
    	while (buf&&ifile.get(ch))
    		buf.put(ch);
    	//返回与流对象buf关联的字符串
    	return buf.str();
    }
    //检测是否已经存在此标识符
    int isexists(string str)
    {
    	for (int i = 0; i < slen; i++)
    		if (str == slabel[i])
    			return 1;
    
    	return 0;
    }
    //检测是否已经存在此常量
    int  isexistc(string con)
    {
    	for (int i = 0; i < clen; i++)
    		if (con == clabel[i])
    			return 1;
    	return -1;
    }
    int isexists()
    {
    	for (int i = 0; i < slen; i++)
    		if (strToken == slabel[i])
    			return i;
    
    	return -1;
    }
    //检测是否已经存在此常量
    int  isexistc()
    {
    	for (int i = 0; i < clen; i++)
    		if (strToken == clabel[i])
    			return i;
    	return -1;
    }
    //名字表的结构体
    struct symbel
    {
    	string name;
    	string kind;
    	int level;
    	int addr;
    	int value;
    }symlabel;
    //判断是否退出
    
    //主程序
    void lex(string file1)
    {
    	int code, value, num = 0;
    	/*cout << "请输入单词长度"<<endl;
    	cin >> num;
    	cout << "请输入单词："<<endl;
    	cin >> input;*/
    	//char filename[] = "test.txt";
    	//const char *file = readFileIntoString(filename).data();
    	std::ifstream in(file1);
    	std::ostringstream tmp;
    	tmp << in.rdbuf();
    	std::string str = tmp.str();
    	cout << str << endl;
    	for (int i = 0; i < str.length(); i++)//如果输入中有大写字母，则转换为小写字母
    		if (str.at(i) <= 90 && str.at(i) >= 65)
    			str.at(i) = str.at(i) + 32;
    	const char *file = str.data();
    	input = file;
    
    	while (input[index] != 0)
    	{
    		len = 0;
    		//strcpy(strToken,"");
    		memset(strToken, 0, sizeof(strToken));
    		//cout << strToken << endl;
    		//Sleep(1000);
    		GetChar();
    		GetBC();
    		if (issLetter())//判断是否是字母
    		{
    			while (issLetter() || isDigit())
    			{
    				concat();
    				GetChar();
    			}
    			Retract();
    			result[ip] = strToken;
    			ip++;
    			code = Reserve();
    			if (code == -1)//不在关键字表里，即为标识符
    			{
    				
    				int index1 = isexists();//检测此标识符是否存在
    				if (index1 != -1)
    					cout << "(" << strToken << ",id," << index1 << ")" << endl;
    				else
    				{
    					value = insertId();
    					cout << "(" << strToken << ",id," << value << ")" << endl;//输出标识符的三元组
    
    				}//cout << strToken<<endl;
    			}
    			else
    			{
    				cout << "(" << klabel[code] << "," << klabel[code] << ",-)" << endl;//输出关键字的二元组
    			}
    		}
    		else if (isDigit())//如果是数字，即为常量
    		{
    			while (isDigit())
    			{
    				concat();
    				GetChar();
    			}
    			Retract();
    			result[ip] = strToken;
    			ip++;
    			int index2 = isexistc();
    			if (index2 != -1)
    				cout << "(" << strToken << ",int," << index2 << ")" << endl;
    			else
    			{
    				value = insertConst();
    				cout << "(" << strToken << ",int," << value << ")" << endl;
    			}
    		}
    		/*else if (islLetter())
    		{
    		while(islLetter())
    		{
    		concat();
    		GetChar();
    		}
    		Retract();
    		code = Reserve();
    		if (code == -1)
    		cout << "拼写错误"<<endl;
    		else
    		cout << "(" << code << ",-)" << endl;//输出关键字的二元组
    		}*/
    		else//其余情况
    		{
    			switch (ch)
    			{
    			case '+':
    				cout << "(+,+," << "-)" << endl;
    				result[ip] = "+";
    				ip++;
    				break;
    			case '-':
    				cout << "(-,-," << "-)" << endl;
    				result[ip] = "-";
    				ip++;
    				break;
    			case '*':
    				cout << "(*,*," << "-)" << endl;
    				result[ip] = "*";
    				ip++;
    				break;
    			case '/':
    				cout << "(/,/," << "-)" << endl;
    				result[ip] = "/";
    				ip++;
    				break;
    			case '=':
    				cout << "(=,=," << "-)" << endl;
    				result[ip] = "=";
    				ip++;
    				break;
    			case '#':
    				cout << "(#,#," << "-)" << endl;
    				result[ip] = "#";
    				ip++;
    				break;
    			case '<':
    				GetChar();
    				if (ch == '=')
    				{
    					cout << "(<=,<=," << "-)" << endl;
    					result[ip] = "<=";
    					ip++;
    				}
    				else
    				{
    					Retract();
    					cout << "(<,<," << "-)" << endl;
    					result[ip] = "<";
    					ip++;
    				}
    				break;
    			case '>':
    				GetChar();
    				if (ch == '=')
    				{
    					cout << "(>=,>=," << "-)" << endl;
    					result[ip] = ">=";
    					ip++;
    				}
    				else
    				{
    					Retract();
    					cout << "(>,>," << "-)" << endl;
    					result[ip] = ">";
    					ip++;
    				}
    				break;
    			case ',':
    				cout << "(,,,," << "-)" << endl;
    				result[ip] = ",";
    				ip++;
    				break;
    			case ';':
    				cout << "(;,;," << "-)" << endl;
    				result[ip] = ";";
    				ip++;
    				break;
    			case ':':
    				GetChar();
    				if (ch == '=')
    				{
    					cout << "(:=,:=," << "-)" << endl;
    					result[ip] = ":=";
    					ip++;
    				}
    				else
    				{
    					Retract();
    					cout << "(:,:," << "-)" << endl;
    					result[ip] = ":";
    					ip++;
    				}
    				break;
    			case '(':
    				cout << "((,(," << "-)" << endl;
    				result[ip] = "(";
    				ip++;
    				break;
    			case ')':
    				cout << "(),)," << "-)" << endl;
    				result[ip] = ")";
    				ip++;
    				break;
    			case '.':
    				cout << "(.,.," << "-)" << endl;
    				result[ip] = ".";
    				ip++;
    				break;
    			case 10://排除掉换行符
    				break;
    			default:
    				cout << "拼写错误:" << ch << endl;
    				break;
    			}
    		}
    	}
    }
    //函数声明
    void subProgram(treeNode<string> *tN);
    void conExplain(treeNode<string> *tN);
    void varExplain(treeNode<string> *tN);
    void processExplain(treeNode<string> *tN);
    void constDef(treeNode<string> *tN);
    void statement(treeNode<string> *tN);
    void varExplain(treeNode<string> *tN);
    void id(treeNode<string> *tN);
    void unsInt(treeNode<string> *tN);
    void dig(treeNode<string> *tN);
    void processHead(treeNode<string> *tN);
    void AssignmentStatement(treeNode<string> *tN);
    void expression(treeNode<string> *tN);
    void CompoundStatement(treeNode<string> *tN);
    void conditions(treeNode<string> *tN);
    void AddAndSubtract(treeNode<string> *tN);
    void item(treeNode<string> *tN);
    void factor(treeNode<string> *tN);
    void MULAndDIV(treeNode<string> *tN);
    void ConditionStatement(treeNode<string> *tN);
    void relationship(treeNode<string> *tN);
    void processCall(treeNode<string> *tN);
    void readStatement(treeNode<string> *tN);
    void dowhile(treeNode<string> *tN);
    void writeStatement(treeNode<string> *tN);
    
    treeNode<string> *Tprogram=new treeNode<string>(2,"<程序>");
    /*treeNode<string> *TsubProgram=new treeNode<string>(4,"<分程序>");
    treeNode<string> *TconExplain = new treeNode<string>("<常量说明部分>");
    treeNode<string> *TvarExplain = new treeNode<string>("<变量说明部分>");
    treeNode<string> *TprocessExplain = new treeNode<string>("<过程说明部分>");
    treeNode<string> *Tstatement = new treeNode<string>(1,"<语句>");
    treeNode<string> *TconstDef = new treeNode<string>(3,"<常量定义>");
    treeNode<string> *TunsInt = new treeNode<string>("<无符号整数>");
    treeNode<string> *Tpoint = new treeNode<string>(".");
    treeNode<string> *TprocessHead = new treeNode<string>(3,"过程首部");
    treeNode<string> *Tid = new treeNode<string>("标识符");
    */
    void  program()//程序
    { 
    	ip = 0;
    	treeNode<string> *TsubProgram = new treeNode<string>(4,"<分程序>");
    	subProgram(TsubProgram);
    	if (result[ip] == ".")
    	{
    		Tprogram->child[0] = TsubProgram;
    		Tprogram->child[1] = new treeNode<string>(".");
    		cout << "成功";
    	}
    	else
    		exit(0);
    }
    
    void subProgram(treeNode<string> *tN)//分程序
    {
    
    	int count = 4;
    	//常量说明部分
    	if (result[ip] == "const")
    	{   
    		treeNode<string> *TconExplain = new treeNode<string>("<常量说明部分>");
    		conExplain(TconExplain);
    		count++;
    		tN->child[0] = TconExplain;
    	}
    	//变量说明部分
    	if (result[ip] == "var")
    	{
    		treeNode<string> *TvarExplain = new treeNode<string>("<变量说明部分>");
    		varExplain(TvarExplain);
    		count++;
    		tN->child[1] = TvarExplain;
    	}
    	//过程说明部分
    	if (result[ip] == "procedure")
    	{
    		treeNode<string> *TprocessExplain = new treeNode<string>("<过程说明部分>");
    		processExplain(TprocessExplain);
    		count++;
    		tN->child[2] = TprocessExplain;
    	}
    	treeNode<string> *Tstatement = new treeNode<string>(1,"<语句>");
    	statement(Tstatement);//语句
    	tN->child[3]=Tstatement;
    	
    }
    void conExplain(treeNode<string> *tN)//常量说明部分
    {
    	if (result[ip] == "const")
    	{
    		ip++;
    		tN->child[0] = new treeNode<string>("const");
    		treeNode<string> *TconstDef1 = new treeNode<string>(3, "常量定义");
    		tN->child[1] = TconstDef1;
    		constDef(TconstDef1);
    		int count = 0;
    		while (result[ip] == ",")
    		{   
    			count++;//树的孩子数
    			tN->child[2*count] = new treeNode<string>(",");
    			treeNode<string> *TconstDef2 = new treeNode<string>(3,"常量定义");
    			tN->child[2*count+1] = TconstDef2;
    			ip++;
    			constDef(TconstDef2);
    		}
    		if (result[ip] == ";")
    		{
    			ip++;
    			//增加树的结构
    			tN->child[2*count + 2] = new treeNode<string>(";");
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void varExplain(treeNode<string> *tN)//变量说明部分
    {
    	if (result[ip] == "var")
    	{
    		ip++;
    		tN->child[0] = new treeNode<string>("var");
    		treeNode<string> *Tid1 = new treeNode<string>(3, "<标识符>");
    		tN->child[1] = Tid1;
    		id(Tid1);
    		int count = 0;
    		while (result[ip] == ",")
    		{
    			ip++;
    			count++;
    			tN->child[2 * count] = new treeNode<string>(",");
    			treeNode<string> *Tid2 = new treeNode<string>(3, "<标识符>");
    			tN->child[2 * count + 1] = Tid2;
    			id(Tid2);
    		}
    	
    		if (result[ip] == ";")
    		{
    			ip++;
    			tN->child[count + 1] = new treeNode<string>(";");
    		}
    	   else
    		   exit(0);
    	}
    	else
    		exit(0);
    }
    void processExplain(treeNode<string> *tN)//过程说明部分
    {
    	treeNode<string> *TprocessHead = new treeNode<string>(3,"<过程首部>");
    	tN->child[0] = TprocessHead;
    	treeNode<string> *TsubProgram = new treeNode<string>( "<分程序>");
    	tN->child[1] = TsubProgram;
    	processHead(TprocessHead);
    	subProgram(TsubProgram);
    	if (result[ip] == ";")
    	{   
    		tN->child[2] = new treeNode<string>(";");
    		ip++;
    		int count=0;
    		while (result[ip]=="procedure")
    		{
    			count++;
    			treeNode<string> *TprocessExplain = new treeNode<string>("<过程说明部分>");
    			tN->child[count + 2] = TprocessExplain;
    			processExplain(TprocessExplain);
    		}
    	}
    	    else
    			exit(0);
    }
    void statement(treeNode<string> *tN)//语句
    {
    	if (isexists(result[ip]))//赋值语句
    	{
    		treeNode<string> *TAssignmentStatement = new treeNode<string>(3,"<赋值语句>");
    		tN->child[0] = TAssignmentStatement;
    		AssignmentStatement(TAssignmentStatement);
    	}
    	else if (result[ip] == "if")//条件语句
    	{
    		treeNode<string> *TConditionStatement = new treeNode<string>(3,"<条件语句>");
    		tN->child[0] = TConditionStatement;
    		ConditionStatement(TConditionStatement);
    	}
    	else if (result[ip] == "while")//当型循环
    	{
    		treeNode<string> *Tdowhile = new treeNode<string>(3,"<当型循环语句>");
    		tN->child[0] = Tdowhile;
    		dowhile(Tdowhile);
    	}
    	else if (result[ip] == "call")//过程调用	
    	{
    		treeNode<string> *Tcall= new treeNode<string>(2, "<过程调用语句>");
    		tN->child[0] = Tcall;
    		processCall(Tcall);
    	}
    	else if (result[ip] == "read")//读语句
    	{
    		treeNode<string> *Tread = new treeNode<string>(2, "<读语句>");
    		tN->child[0] = Tread;
    		readStatement(Tread);
    	}
    	else if (result[ip] == "write")//写语句	
    	{
    		treeNode<string> *Twrite = new treeNode<string>(2, "<写语句>");
    		tN->child[0] = Twrite;
    		writeStatement(Twrite);
    	}
    	else if (result[ip] == "begin")//复合语句
    	{
    		treeNode<string> *TCompoundStatement = new treeNode<string>(2, "<复合语句>");
    		tN->child[0] = TCompoundStatement;
    		CompoundStatement(TCompoundStatement);
    	}
    	
    }
    void constDef(treeNode<string> *tN)//常量定义
    { 
    	treeNode<string> *Tid = new treeNode<string>( "<标识符>");
    	tN->child[0] = Tid;
    	id(Tid);
    	if (result[ip] == "=")
    	{
    		tN->child[1] = new treeNode<string>("=");
    		ip++;
    		treeNode<string> *TunsInt = new treeNode<string>("<无符号整数>");
    		tN->child[2] = TunsInt;
    		unsInt(TunsInt);
    	}
    	else
    		exit(0);
    }
    
    void id(treeNode<string> *tN)//标识符
    {
    	if (isexists(result[ip]))
    	{
    		tN->child[0] = new treeNode<string>(result[ip]);
    		ip++;
    	}
    	else
    		exit(0);
    }
    void unsInt(treeNode<string> *tN)//无符号整数
    {
    	if (isexistc(result[ip]))
    	{
    		tN->child[0] = new treeNode<string>(result[ip]);
    		ip++;
    	}
    	else
    		exit(0);
    }
    
    void dig(treeNode<string> *tN)//数字
    {
    	if (result[ip].at(0) <= 57 && result[ip].at(0) >= 48)
    	{
    		ip++;
    		tN->child[0] = new treeNode<string>(result[ip]);
    	}
    	else
    		exit(0);
    }
    void processHead(treeNode<string> *tN)//过程首部
    {
    	if (result[ip] == "procedure")
    	{
    		ip++;
    		tN->child[0] = new treeNode<string>("procedure");
    		treeNode<string> *Tid = new treeNode<string>("<标识符>");
    		tN->child[1] = Tid;
    		id(Tid);
    		if (result[ip] == ";")
    		{
    			ip++;
    			tN->child[1] = new treeNode<string>(";");
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void AssignmentStatement(treeNode<string> *tN)//赋值语句
    {
    	treeNode<string> *Tid = new treeNode<string>("<标识符>");
    	tN->child[0] = Tid;
    	id(Tid);
    	if (result[ip] == ":=")
    	{
    		ip++;
    		tN->child[1] = new treeNode<string>(":=");
    		treeNode<string> *Texpression = new treeNode<string>("<表达式>");
    		tN->child[3] = Texpression;
    		expression(Texpression);
    	}
    	else
    		exit(0);
    }
    void expression(treeNode<string> *tN)//表达式
    {
    	if (result[ip] == "+" || result[ip] == "-")
    	{
    		ip++;
    		tN->child[0] = new treeNode<string>(result[ip]);
    	}
    	treeNode<string> *Titem = new treeNode<string>("<项>");
    	tN->child[1]=Titem;
    	item(Titem);
    	int count = 0;
    	while (result[ip] == "+" || result[ip] == "-")
    	{
    		count++;
    		treeNode<string> *TAddAndSubtract = new treeNode<string>("<加减运算符>");
    		tN->child[2*count] = TAddAndSubtract;
    		treeNode<string> *Titem = new treeNode<string>("<项>");
    		tN->child[2 * count+1] = Titem;
    		AddAndSubtract(TAddAndSubtract);
    		item(Titem);
    	}
    	
    }
    void CompoundStatement(treeNode<string> *tN)//复合语句
    {
    	if (result[ip] == "begin")
    	{
    		tN->child[0] = new treeNode<string>("begin");
    		ip++;
    		treeNode<string> *Tstatement1 = new treeNode<string>("<语句>");
    		tN->child[1] = Tstatement1;
    		statement(Tstatement1);
    		int count = 0;
    		while (result[ip] == ";")
    		{
    			ip++;
    			count++;
    			tN->child[2 * count] = new treeNode<string>(";");
    			treeNode<string> *Tstatement2 = new treeNode<string>("<语句>");
    			tN->child[2 * count + 1] = Tstatement2;
    			statement(Tstatement2);
    
    		}
    		if (result[ip] == "end")
    		{
    			tN->child[2 * count+2] = new treeNode<string>("end");
    			ip++;
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    
    }
    void conditions(treeNode<string> *tN)//条件
    { 
    	
    	 if (result[ip] == "odd")
    	 {
    		 ip++;
    		 tN->child[0] =new  treeNode<string>("odd");
    		 treeNode<string> *Texpression = new treeNode<string>("<表达式>");
    		 tN->child[1] = Texpression;
    		 expression(Texpression);
    	}
    	 else 
    	{
    		 treeNode<string> *Texpression1 = new treeNode<string>("<表达式>");
    		 tN->child[0] = Texpression1;
    		expression(Texpression1);
    		treeNode<string> *Trealationship = new treeNode<string>("<关系运算符>");
    		tN->child[1] = Trealationship;
    		relationship(Trealationship);
    		treeNode<string> *Texpression2 = new treeNode<string>("<表达式>");
    		tN->child[2] = Texpression2;
    		expression(Texpression2);
    	}
    }
    void item(treeNode<string> *tN)//项
    {
    	treeNode<string> *Tfactor1 = new treeNode<string>("<因子>");
    	tN->child[0] = Tfactor1;
    	factor(Tfactor1);
    	int count = 0;
    	while (result[ip]=="*"|| result[ip] == "/")
    	{
    		count++;
    		treeNode<string> *TMULAndDIV = new treeNode<string>("<乘除运算符>");
    		tN->child[2*count-1] = TMULAndDIV;
    		MULAndDIV(TMULAndDIV);
    		treeNode<string> *Tfactor2 = new treeNode<string>("<因子>");
    		tN->child[2*count] = Tfactor2;
    		factor(Tfactor2);
    	}
    }
    void factor(treeNode<string> *tN)//因子
    {
    	if ((result[ip].at(0) <= 122 && result[ip].at(0) >= 97))
    	{
    		treeNode<string> *Tid = new treeNode<string>("<标识符>");
    		tN->child[0] = Tid;
    		id(Tid);
    	}
    	else if ((result[ip].at(0) <= 57 && result[ip].at(0) >= 48))
    	{
    		treeNode<string> *TunsInt = new treeNode<string>("<无符号整数>");
    		tN->child[0] = TunsInt;
    		unsInt(TunsInt);
    	}
    	else if ((result[ip] == "("))
    	{
    		tN->child[0] = new treeNode<string>("(");
    		treeNode<string> *Texpression = new treeNode<string>("<表达式>");
    		tN->child[1] = Texpression;
    		expression(Texpression);
    		if (result[ip] == ")")
    		{
    			tN->child[2] = new treeNode<string>(")");
    			ip++;
    		}
    		else
    			exit(0);
     	}
    	else
    		exit(0);
    
    }
    void AddAndSubtract(treeNode<string> *tN)//加减运算符
    {
    	if (result[ip] == "+" || result[ip] == "-")
    	{
    		tN->child[0] = new treeNode<string>(result[ip]);
    		ip++;
    	}
    	else
    		exit(0);
    }
    void MULAndDIV(treeNode<string> *tN)//乘除运算符
    {
    	if (result[ip] == "*" || result[ip] == "/")
    	{
    		tN->child[0] = new treeNode<string>(result[ip]);
    		ip++;
    	}
    	else
    		exit(0);
    }
    void relationship(treeNode<string> *tN)//关系运算符
    {
    	if (result[ip] == "=" || result[ip] == "#"||result[ip]=="<"|| result[ip] == "<="||result[ip] == ">"
    		||result[ip] == ">=")
    	{
    		tN->child[0] = new treeNode<string>(result[ip]);
    		ip++;
    	}
    	else
    		exit(0);
    }
    void ConditionStatement(treeNode<string> *tN)//条件语句
    {
    	if (result[ip] == "if")
    	{
    		tN->child[0] = new treeNode<string>("if");
    		ip++;
    		treeNode<string> *Tconditions = new treeNode<string>("<条件>");
    		tN->child[1] = Tconditions;
    		conditions(Tconditions);
    		if (result[ip] == "then")
    		{
    			ip++;
    			tN->child[0] = new treeNode<string>("then");
    			treeNode<string> *Tstatement = new treeNode<string>("<语句>");
    			tN->child[1] = Tstatement;
    			statement(Tstatement);
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void processCall(treeNode<string> *tN)//过程调用语句
    {
    	if (result[ip] == "call")
    	{
    		ip++;
    		treeNode<string> *Tid = new treeNode<string>("<标识符>");
    		tN->child[0] = Tid;
    		id(Tid);
    	}
    	else
    		exit(0);
    }
    void dowhile(treeNode<string> *tN)//当型循环
    {
    	if (result[ip] == "while")
    	{
    		tN->child[0] = new treeNode<string>("while");
    		ip++;
    		treeNode<string> *Tconditions = new treeNode<string>("<条件>");
    		tN->child[1] = Tconditions;
    		conditions(Tconditions);
    		if (result[ip] == "do")
    		{
    			tN->child[2] = new treeNode<string>("do");
    			ip++;
    			treeNode<string> *Tstatement = new treeNode<string>("<语句>");
    			tN->child[3] = Tstatement;
    			statement(Tstatement);
    		}
    		else
    			success = 0;
    	}
    	else
    		exit(0);
    }
    void readStatement(treeNode<string> *tN)//读语句
    {
    	if (result[ip] == "read")
    	{
    		tN->child[0] = new treeNode<string>("read");
    		ip++;
    		if (result[ip] == "(")
    		{
    			tN->child[1] = new treeNode<string>("（");
    			ip++;
    			treeNode<string> *Tid1 = new treeNode<string>("<标识符>");
    			tN->child[2] = Tid1;
    			id(Tid1);
    			int count = 0;
    			while (result[ip] == ",")
    			{
    				count++;
    				tN->child[2*count+1] = new treeNode<string>(",");
    				ip++;
    				treeNode<string> *Tid2 = new treeNode<string>("<标识符>");
    				tN->child[2*count+2] = Tid2;
    				id(Tid2);
    
    			}
    			if (result[ip] == ")")
    			{
    				tN->child[2*count+3] = new treeNode<string>(")");
    				ip++;
    			}
    			else
    				exit(0);
    
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }
    void writeStatement(treeNode<string> *tN)//写语句
    {
    	if (result[ip] == "write")
    	{
    		tN->child[0] = new treeNode<string>("write");
    		ip++;
    		if (result[ip] == "(")
    		{
    			ip++;
    			tN->child[1] = new treeNode<string>("(");
    			treeNode<string> *Texpression1 = new treeNode<string>("<表达式>");
    			tN->child[2] = Texpression1;
    			expression(Texpression1);
    			int count = 0;
    			while (result[ip] == ",")
    			{
    				count++;
    				ip++;
    				tN->child[2 * count + 1] = new treeNode<string>(",");
    				treeNode<string> *Texpression2 = new treeNode<string>("<表达式>");
    				tN->child[2 * count + 2] = Texpression2;
    				expression(Texpression2);
    
    			}
    			if (result[ip] == ")")
    			{
    				tN->child[2 * count + 3] = new treeNode<string>(")");
    				ip++;
    			}
    			else
    				exit(0);
    
    		}
    		else
    			exit(0);
    	}
    	else
    		exit(0);
    }

测试文本：

const c1=2;
    var v1,v2,v3,v4;
    procedure p1;
     var v5;
     begin
      v5:=2;
      write(v5/2+2-1);
      while v3#0 do
      begin
       v4:=v1/v2;
       v3:=v1-v4*v2;
       v1:=v2;
       v2:=v3;
      end;
     end;
    procedure p2;
     const c2=2;
     procedure p3;
      begin
       if v1#1 then
       begin
        v1:=v1-1;  
        v2:=v2*v1;
        call p3;
       end;
      end;
     begin
      call p3;
      if odd c2 then
       write(c2);
      if c2=2 then
       write(c2+1)
     end;
    begin
     read(v1,v2);
     if v1<v2 then
     begin
      v3:=v1;
      v1:=v2;
      v2:=v3;
     end;
     begin;
      v3:=1;
      call p1;
      write(c1,c1*v1,c1*v1/2);
     end;
     read(v1);
     v2:=v1;
     call p2;
     write(v2);
    end.

测试效果（有点大，没显示完）：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MjQ3NTQ0_size_16_color_FFFFFF_t_70][]

源码：[https://github.com/yanguojun123/Compile][https_github.com_yanguojun123_Compile]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MjQ3NTQ0_size_16_color_FFFFFF_t_70]: /images/20220413/1d5188c501aa4270a16d78f91a48bc4c.png
[https_github.com_yanguojun123_Compile]: https://github.com/yanguojun123/Compile