流程控制

曾经终败给现在 2023-08-17 16:08 127阅读 0赞

**1、顺序结构**

**2、if条件语句**

判断输入的字符是否为大写字母（if......else........）：

package 选择结构;
    
    import java.util.Scanner;
    public class IfDemo {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        String s = sc.next();//返回 指定索引处的值。
        char c = s.charAt(0);
        if(c>=65&&c<=90)
            System.out.println("大写字母");
        else
            System.out.println("其他");
    }
    }

**3、switch选择语句**

import java.util.*;
    public class SwitchDemo 
    {
    public static void main(String [] args)
    {
    int num1,num2,num;
    String c;
    Scanner reader=new Scanner(System.in);
    System.out.println("输入正整数·");
    num1=reader.nextInt();
    System.out.println("输入运算符");
    c=reader.next();
    System.out.println("输入正整数");
    num2=reader.nextInt();
    switch(c)
    {
    case"+":System.out.println("num1+num2="+(num1+num2));break;
    case"-":System.out.println("num1-num2="+(num1+num2));break;
    case"/":System.out.println("num1/num2="+(num1/num2));break;
    case"*":System.out.println("num1*num2="+(num1*num2));break;
    }
    }
    }

**4、while语句**

package WhileDemo;
    
    import java.util.Scanner;
    
    public class WhileDemo {
    public static void main(String[] args) {
        int i=2,n;
        float  fac=1;
        System.out.println("请输入一个正整数");
        Scanner sc=new Scanner(System.in);
        n=sc.nextInt();
        if(n==0||n==1){
            System.out.println(1);
        }
        while(i<=n){
            fac=fac*i;
            i++;
        }
        System.out.println(fac);
    }
    }

**5、do......while（）语句**

package DOWhileDemo;
    
    import java.util.Scanner;
    
    public class DoWhileDemo {
        public static void main(String[] args) {
            Scanner sc=new Scanner(System.in);
            int n=sc.nextInt();
            int x=1,add=0;
            do {
                add=add+x;
                x++; // 将x的值自增
            } while (x <= n); // 循环条件
            System.out.println(add);
    
        }
    
    }

**6、for循环语句**

package 九九乘法表;
    
    public class MultiplicationTable {
        public static void main(String[] args) {
            for (int i = 1; i <= 9; i++) {
                System.out.println("\n");
                for (int j = 1; j <= i; j++) {
                    System.out.print(i + "*" + j + "=" + i * j + "  ");
                }
            }
        }
    }

![1392562-20190728161435431-1994997643.png][]

**7、无限循环（死循环）**

while(true)\{\}

和

for(;;)\{\}

转载于:https://www.cnblogs.com/zhai1997/p/11258254.html

[1392562-20190728161435431-1994997643.png]: /images/20230810/94ba5bca8b17436ab30fe06ecce6cfd7.png