#include<stdio.h>
int main()
{
    float data1,data2;
    int c;
    system("cls");
    printf("\t\t|-------------------------------------|\n");
    printf("\t\t|           实用计算机                |\n");
    printf("\t\t|-------------------------------------|\n");
    printf("\t\t|            1---加法                 |\n");
    printf("\t\t|            2---减法                 |\n");
    printf("\t\t|            3---乘法                 |\n");
    printf("\t\t|            4---除法                 |\n");
    printf("\t\t|            0---退出                 |\n");
    printf("\t\t|-------------------------------------|\n");
    printf("请选择表中数字:");
    scanf("%d",&c);
    while(c<=4&&c>=1)
    {
    scanf("%f%f",&data1,&data2);
    switch(c)
    {
        case 1:printf("%f\n",data1+data2);break;
        case 2:printf("%f\n",data1-data2);break;
        case 3:printf("%f\n",data1*data2);break;
        case 4:if(data2!=0)
                printf("%.2f\n",data1/data2);
                else
                printf("数据错误，除数不为零\n");break;
    }
    }
   
}

   if(c<=4&&c>=1)

[ 本帖最后由 纳兰伽香 于 2015-4-21 22:34 编辑 ]

#include<stdio.h>
int  main()
{
    float data1,data2;
    int c;
    system("cls");
   
    while(1)
    {
        printf("\t\t|-------------------------------------|\n");
        printf("\t\t|           实用计算机                |\n");
        printf("\t\t|-------------------------------------|\n");
        printf("\t\t|            1---加法                 |\n");
        printf("\t\t|            2---减法                 |\n");
        printf("\t\t|            3---乘法                 |\n");
        printf("\t\t|            4---除法                 |\n");
        printf("\t\t|            0---退出                 |\n");
        printf("\t\t|-------------------------------------|\n");
        printf("请选择表中数字:");
        scanf("%d",&c);
        if(c==0) return 0;
        else
        {    printf("请输入date1和date2：\n");
        scanf("%f%f",&data1,&data2);
    switch(c)
    {
        case 1:printf("%f\n",data1+data2);break;
        case 2:printf("%f\n",data1-data2);break;
        case 3:printf("%f\n",data1*data2);break;
        case 4:if(data2!=0)
                printf("%.2f\n",data1/data2);
                else
                printf("数据错误，除数不为零\n");break;
         
    }
    }
    }
    return 0;
   
}

while(c<=4&&c>=1)如果为真就一直在循环。

如果只是进行一次的加减乘除的运算的 话就不要用while就好了!

你的while语句可以换
while(scanf(“%d”, &c)!=EOF)
    if(c<=4&&c>=1){……}
试试

在哪加if

就是想要运算过后再判断一次是否进入循环

就是想要多次循环

在while后面