还有while (num=0)改为while (num!=0)

while(num!=0);

#include <stdio.h>
void main()
{
       int i;
       printf("        主菜单\n");
       printf("===========================\n");
       printf("   1.输入功能\n");
       printf("   2.按学号查找\n");
       printf("   3.打印输出\n");
       printf("   0.退出\n");
       printf("===========================\n");
       printf("   请选择(0~3)\n");
        do
        {
            scanf_s("%d",&i);
            {
           switch(i)
                {
                case 0:printf("谢谢使用\n");break;
                case 1:printf("请输入\n");break;
                case 2:printf("请输入查找学生学号\n");break;
                case 3:printf("正在输出\n");break;
                default:printf("输入错误，请重新输入\n");
                }
            }
        }
            while(i!=0);
}


//给你参考我编写的,利用do-while会先执行一次的特点，所以我们可以把0直接内嵌到switch里面去。最开始想用while来做，那个0的问题处理了好久都没有搞定……

我开始也是这么编写的后来用字母就 死循环了

#include <stdio.h>
main ()
{ char n;int m=1;
do
{
scanf("%c",&n);
switch (n)
{
case '\n" break;
case '0' : m=0;printf("谢谢使用\n");break;
case '1' : printf("请输入\n");break;
case '2' : printf("请输入查询学生学号\n");break;
case '3' : printf("正在输入\n");break;
default : printf("输入错误，请重新输入\n"); }
}
while (m);
}



[ 本帖最后由 sorauo 于 2012-9-25 17:41 编辑 ]

#include <stdio.h>

void main()
{
        int num,choice;
        do
        {
           printf("Menu%-6\n1.Put in students results\n2.Inquire students results\n3.Print out result\n0.Exit\n");
           printf("Please choose(0-3):");
           scanf("%d",&num);
           switch(choice)  //请问你要选择什么 num
           {
           case 1: printf("Please enter\n"); break;
           case 2: printf("Please enter the student number\n"); break;
           case 3: printf("Printing!\n"); break;
           default: printf("Input wrong!");
           }
       }
       while (num=0);//判断错误while(num！=0);
       print("Thank you");//打错printf
}