C++重载赋值语句

曾经终败给现在 2022-05-25 01:29 194阅读 0赞

建立一个字符串类名为String，至少写出`三个构造函数`，重载赋值`等号=、加号+、关系等于==、>、>=、<、<=，`另写出析构函数和其他的成员函数，如求字符串的长度、输出字符串等。在main（）中定义String类对象测试所写函数是否正确。

#include <iostream>
    #include <vector>
    #include <algorithm>
    #include <stdlib.h>
    #include <string.h>
    #include <stdio.h>
    using namespace std;
    
    class Str{
    private:
        char *str;
        char length;
    public:
        Str():str(NULL), length(0){}
        Str(const Str &s){
            length = s.length;
            str = (char*)malloc((length + 1)*sizeof(char));
            strcpy(str, s.str);
        }
        Str(char *s, int l){
            str = (char*)malloc((l+1)*sizeof(char));
            strcpy(str, s);
            length = l;
        }
        int size(){ return length;  }
        Str& operator+(const Str &s){
            char *ss = (char*)malloc((s.length + length+1)*sizeof(char));
            //length = s.length + length;
            strcpy(ss, str);
            strcat(ss, s.str);
            //free(str);
            //return Str(ss, s.length + length);
            str = ss;
            return *this;
        }
        Str& operator+=(const Str &s){
            char *ss = (char*)malloc((s.length + length + 1)*sizeof(char));
            length = s.length + length;
            strcpy(ss, str);
            free(str);
            strcat(ss, s.str);
            str = ss;
            return *this;
        }
        int operator<=(const Str &s){
            if(strcmp(s.str, str) >= 0 )
                return 1;
            else
                return 0;
        }
        Str& operator=(const Str &s){
            if (this == &s) return *this;
            length = s.length;
            char *ss = (char*)malloc((length + 1)*sizeof(char));
            free(str);
            strcpy(ss, s.str);
            str = ss;
            return *this;
        }
    
        bool operator==(const Str &s){
            if (s.length != length) return false;
            else return strcmp(s.str, str) == 0;
        }
    
        friend ostream &operator<<(ostream &out, Str &ss){
            out << ss.str;
            return out;
        }
        ~Str()
        {
            free(str);
        }
    };
    
    
    int main()
    {
        char s[100], s2[100];
        strcpy(s, "this is my string");
        strcpy(s2, "this is my house");
        Str str(s, strlen(s));
        Str str2(s2, strlen(s2));
        cout << "(str):\t" << str << endl;
        cout << "(str2):\t" << str2 << endl;
        cout << "(str < str2):\t" << (str<=str2) <<endl;
        cout << "sum(str + str2):\t" << str+str2 << endl;
        cout << "(str):\t" << str << endl;
        cout << "(str2):\t" << str2 << endl;
        str += str2;
        cout << "excute (str += str2) str = \t" << str << endl;
        cout << "(str2):\t" << str2 << endl;
        str = str2;
        cout << "excute (str = str2) str = \t" << str << endl;
        cout << "(str2):\t" << str2 << endl;
        Str str4 = str2;
        cout << "excute (str4 = str2) str2 = \t" << str2 << endl;
        cout << "(str4):\t" << str4 << endl;
        cout << "(str4 < str2):\t" << (str4<=str2) <<endl;
        return 0;
    }