C语言第四章分支结构练习

川长思鸟来 2021-11-17 05:46 417阅读 0赞

**目录**

*  [一、输入语文，数学成绩，根据平均分分3档][3]
 *  [二、使用switch实现算术运算][switch]
 *  [三、使用多重if实现算术运算][if]
 *  [四、for循环][for]
 *  [五、while循环][while]
 *  [六、do while循环][do while]
 *  [七、密码示例][Link 1]
 *  [八、多重if实现计算月份天数][if 1]
 *  [九、switch实现计算月份天数][switch 1]
 *  [十、计算闰年][Link 2]
 *  [十一、判断素数][Link 3]
 *  [十二、100内所有素数][100]
 *  [十三、switch实现输入数字与符号运算结果][switch 2]
 *  [十四、多重if实现输入数字与符号运算结果][if 2]

# 一、输入语文，数学成绩，根据平均分分3档 #

![复制代码][copycode.gif]

#include "stdio.h"
    void main()
    {
        //接受用户输入
        float chinese,math,avg;
        printf("请输入语文成绩：");
        scanf("%f",&chinese);
        printf("请输入数学成绩：");
        scanf("%f",&math);
        
        //判断输入是否正确
        if((chinese>=0&&chinese<=100)&&(math>=0&&math<=100))
        {
           //求平均分
           avg=(chinese+math)/2;
           //根据平均分分档
           if(avg>=0&&avg<=59){
              printf("C");
           }
           else if(avg>=60 && avg<=84)
           {
                 printf("B");
           }
           else
           {
                 printf("A");
           }
        }
        else
        {
            printf("输入错误");
        }
    }

![复制代码][copycode.gif]

![63651-20161025154733906-1598784401.png][]

# 二、使用switch实现算术运算 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        //输入部分
        int d1,d2;
        char o;
        
        printf("d1=");
        scanf("%d",&d1);
        
        fflush(stdin);
        
        printf("运算符（+ - * /）：");
        scanf("%c",&o);
        
        fflush(stdin);
        
        printf("d2=");
        scanf("%d",&d2);
        
        switch(o)
        {
            case '+':
                printf("%d%c%d=%d",d1,o,d2,d1+d2);
                break;
            case '-':
                printf("%d%c%d=%d",d1,o,d2,d1-d2);
                break;
            case '*':
                printf("%d%c%d=%d",d1,o,d2,d1*d2);
                break;
            case '/':
                if(d2!=0)
                {
                    printf("%d%c%d=%d",d1,o,d2,d1/d2);
                }
                else
                {
                    printf("除数不能为零");
                }
                break;
            default:
                printf("系统不支持该运算符。");
        }
        
    }

![复制代码][copycode.gif]

![63651-20161025155029875-1595818629.png][]

# 三、使用多重if实现算术运算 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        //输入部分
        int d1,d2;
        char o;
        
        printf("d1=");
        scanf("%d",&d1);
        
        fflush(stdin);
        
        printf("运算符（+ - * /）：");
        scanf("%c",&o);
        
        fflush(stdin);
        
        printf("d2=");
        scanf("%d",&d2);
        
        if(o=='+')
        {
            printf("%d%c%d=%d",d1,o,d2,d1+d2);
        }
        else if(o=='-')
        {
            printf("%d%c%d=%d",d1,o,d2,d1-d2);
        }
        else if(o=='*')
        {
            printf("%d%c%d=%d",d1,o,d2,d1*d2);
        }
        else if(o=='/')
        {
            if(d2!=0)
            {
                printf("%d%c%d=%d",d1,o,d2,d1/d2);
            }
            else
            {
                printf("除数不能为零");
            }
        }
        else 
        {
            printf("系统不支持该运算符。");
        }
        
    }

![复制代码][copycode.gif]

![63651-20161025155219828-1947917192.png][]

# 四、for循环 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        //1+2+3+4....+58=?
        int i,sum=0;
        for(i=1;i<=58;i++)
        {
            sum=sum+i;
            printf("\n%d",i);
        }
        printf("总和=%d",sum);
    }

![复制代码][copycode.gif]

![63651-20161025155333406-541112157.png][]

# 五、while循环 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int i=1;
        while(i<=100)
        {
            printf("%d \n",i);
            i++;
        }
    }

![复制代码][copycode.gif]

![63651-20161025160525875-115560906.png][]

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int i=1;
        while(1)  //默认条件为真
        {
            printf("%d \n",i);
            i++;
            if(i==100)
            {
                break;  //结束循环
            }
        }
    }

![复制代码][copycode.gif]

![63651-20161025160323625-1651653864.png][]

# 六、do while循环 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int i=0;
        do
        {
            i++;
            printf("%d\n",i);
        }while(i<58);
    }

![复制代码][copycode.gif]

![63651-20161025160746125-677882070.png][]

# 七、密码示例 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int mm,e=0;  //输入次数
        do{
            printf("还有%d次机会",3-e);
            printf("请输入密码：");
            scanf("%d",&mm);
            e++;
        }while(mm!=9527&&e<3);
        
        if(e<=3&&mm==9527)
        {
          printf("密码正确，欢迎进入系统。"); 
        }
        else
        {
           printf("卡已被锁，明天带身份证来。");
        }
    }

![复制代码][copycode.gif]

![63651-20161025160905953-826030608.png][]

![63651-20161025162336921-442214982.png][]

# 八、多重if实现计算月份天数 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        //1 3 5 7 8 10 12 ->31
        //4 6 9 11 ->30
        //13 输入错误
        int month,year;
        printf("请输入年：");
        scanf("%d",&year);
        printf("请输入月：");
        scanf("%d",&month);
        
        if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
        {
          printf("这个月有31天");
        }
        else if(month==4||month==6||month==9||month==11)
        {
          printf("这个月有30天");    
        }
        else if(month==2)
        {
           //①、非整百年能被4整除的为闰年。（如2004年就是闰年,2100年不是闰年）
           //②、能被400整除的是闰年。(如2000年是闰年，1900年不是闰年)
          //如果年被4整除且不被100整除，或400整除
          if(year%4==0&&year%100!=0||year%400==0)
          {
              printf("闰年29天");
          }
          else
          {
              printf("平年28天");
           }
        }
        else 
        {
            printf("输入有误");
        }
         
    }

![复制代码][copycode.gif]

![63651-20161031092040080-1358961583.png][]

# 九、switch实现计算月份天数 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int month,year;
        printf("请输入年：");
        scanf("%d",&year);
        printf("请输入月：");
        scanf("%d",&month);
        
        switch(month)
        {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                printf("31天");
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                printf("30天");
                break;
            case 2:
                if(year%4==0&&year%100!=0||year%400==0)
                {
                    printf("29");
                }
                   else
                {
                    printf("28");
                }
                break;
            default:
                printf("输入错误");
        }
    }

![复制代码][copycode.gif]

![63651-20161031105826924-1747361662.png][]

# 十、计算闰年 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        //被4整除且不被100整除，或被400整除
        int year;
        scanf("%d",&year);
        
        if((year%4==0&&year%100!=0)||(year%400==0))
        {
            printf("闰年");
        }else
        {
             printf("平年");
        }
        
    }

![复制代码][copycode.gif]

![63651-20161031105949393-1032160272.png][]

# 十一、判断素数 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int i,j,flag=1;  //就是素数 树旗，假定默认就是
        scanf("%d",&j);
         
        for(i=2;i<j/2;i++)
        {
            if(j%i==0)
            {
                flag=0;
                break;
            }
        }
        
        if(flag==1)
        {
            printf("素数\n");
        }
        else
        {
            printf("非素数\n");
        }
    }

![复制代码][copycode.gif]

![63651-20161031110304908-537805411.png][]

![63651-20161031110325721-503303537.png][]

# 十二、100内所有素数 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int i,j,flag=1;  //就是素数 树旗
        
        for(j=2;j<=100;j++)
        {
            flag=1;
            for(i=2;i<j;i++)
            {
                if(j%i==0)
                {
                    flag=0;
                    break;
                }
            }
        
            printf("%d",j);
            if(flag==1)
            {
                printf("素数\n");
            }
            else
            {
                printf("非素数\n");
            }
        }
    }

![复制代码][copycode.gif]

![63651-20161031110435518-1094411694.png][]

# 十三、switch实现输入数字与符号运算结果 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int n1,n2;
        char op;
        
        scanf("%d",&n1);
        fflush(stdin);
        
        scanf("%c",&op);
        fflush(stdin);
        
        scanf("%d",&n2);
        
        switch(op)
        {
            case '+':
                printf("%d+%d=%d",n1,n2,n1+n2);
                break;
            case '-':
                printf("%d-%d=%d",n1,n2,n1-n2);
                break;
            case '*':
                printf("%dx%d=%d",n1,n2,n1*n2);
                break;
            case '/':
                if(n2==0)
                {
                    printf("除数不能为零");
                }
                else
                {
                    printf("%d/%d=%d",n1,n2,n1/n2);
                }
                break;
            default:
                printf("符号错误");
        }
    }

![复制代码][copycode.gif]

![63651-20161031110739096-1057104160.png][]

# 十四、多重if实现输入数字与符号运算结果 #

![复制代码][copycode.gif]

/* Note:Your choice is C IDE */
    #include "stdio.h"
    void main()
    {
        int n1,n2;
        char op;
        
        scanf("%d",&n1);
        fflush(stdin);
        
        scanf("%c",&op);
        fflush(stdin);
        
        scanf("%d",&n2);
        
        if(op=='+')
        {
            printf("%d+%d=%d",n1,n2,n1+n2);
        }
        else if(op=='-')
        {
            printf("%d-%d=%d",n1,n2,n1-n2);
        }
        else if(op=='x')
        {
            printf("%dx%d=%d",n1,n2,n1*n2);
        }
        else if(op=='/')
        {
               if(n2==0)
                {
                    printf("除数不能为零");
                }
                else
                {
                    printf("%d/%d=%d",n1,n2,n1/n2);
                }
        }
        else
        {
            printf("符号错误");
        }
    }

![复制代码][copycode.gif]

![63651-20161031110811971-1663084496.png][]

转载于:https://www.cnblogs.com/Jansens520/p/6538188.html

[3]: http://www.cnblogs.com/best/p/5997159.html#_label0
[switch]: http://www.cnblogs.com/best/p/5997159.html#_label1
[if]: http://www.cnblogs.com/best/p/5997159.html#_label2
[for]: http://www.cnblogs.com/best/p/5997159.html#_label3
[while]: http://www.cnblogs.com/best/p/5997159.html#_label4
[do while]: http://www.cnblogs.com/best/p/5997159.html#_label5
[Link 1]: http://www.cnblogs.com/best/p/5997159.html#_label6
[if 1]: http://www.cnblogs.com/best/p/5997159.html#_label7
[switch 1]: http://www.cnblogs.com/best/p/5997159.html#_label8
[Link 2]: http://www.cnblogs.com/best/p/5997159.html#_label9
[Link 3]: http://www.cnblogs.com/best/p/5997159.html#_label10
[100]: http://www.cnblogs.com/best/p/5997159.html#_label11
[switch 2]: http://www.cnblogs.com/best/p/5997159.html#_label12
[if 2]: http://www.cnblogs.com/best/p/5997159.html#_label13
[copycode.gif]: /images/20211116/286fafa034ba49b9ac8f8a613c027005.png
[63651-20161025154733906-1598784401.png]: /images/20211116/c1b4d740204941ae9b4bc1c6db11185d.png
[63651-20161025155029875-1595818629.png]: /images/20211116/f997eae203d54178a4d8388e0fb9a798.png
[63651-20161025155219828-1947917192.png]: /images/20211116/579d085d719b46efad68d87f8dd57800.png
[63651-20161025155333406-541112157.png]: /images/20211116/262a0a11a67247849b0cf515eeb353ce.png
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[63651-20161025162336921-442214982.png]: /images/20211116/f9b5b43480c24827aa54d116e8b5502e.png
[63651-20161031092040080-1358961583.png]: /images/20211116/aad23a59d9a240399b2f4d1aabaf1f4f.png
[63651-20161031105826924-1747361662.png]: /images/20211116/8e3be36a04ce464c9f4aa0b058fbd088.png
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[63651-20161031110304908-537805411.png]: /images/20211116/be1b8d5b4ddf48e186f444903f895b95.png
[63651-20161031110325721-503303537.png]: /images/20211116/23536d62eb584bc4ab7d07ee6e09e660.png
[63651-20161031110435518-1094411694.png]: /images/20211116/acd9ecd3b6344087b639b2cb77404c0a.png
[63651-20161031110739096-1057104160.png]: /images/20211116/7fea2d26f49c4042bff8a44c6bdd8309.png
[63651-20161031110811971-1663084496.png]: /images/20211116/11309053d0f944f1bbb2e0d9b631b87e.png