请看下面一个程序：#include <stdio.h>
int main(void)
{   int choice, i;   double price;
    for( i = 1; i <= 5; i++)
    {   
        printf("[1] Select crisps \n");
        printf("[2] Select popcorn \n");
        printf("[3] Select chocolate \n");
        printf("[4] Select cola \n");
        printf("[0] exit \n");
        printf("Enter choice: ");
        scanf("%d", &choice);   
        switch (choice)
        {         
           case 1: price=3.0;  break;
           case 2: price=2.5;  break;
           case 3: price=4.0;  break;
           case 4: price=3.5;  break;
           default: price=0.0;  break;
        }
        printf("price = %0.1f\n", price);  
    }
    printf("Thanks \n");
   
}
为什么在运行的时候，每输入数字后按回车执行，需一次一次的，直到五次结束。而输入“=”这类字符时，输入第一个敲回车后面的五个都一起出来了？

不懂 帮顶了

#include<stdio.h>
int main(void)
{   int choice, i;   double price;
    for( i = 1; i <= 5; i++)
    {   
        printf("[1] Select crisps \n");
        printf("[2] Select popcorn \n");
        printf("[3] Select chocolate \n");
        printf("[4] Select cola \n");
        printf("[0] exit \n");
        printf("Enter choice: ");
        scanf("%d", &choice);   
        getchar();            //这里加一个getchar()来接回车,就行了.
        switch (choice)
        {         
           case 1: price=3.0;  break;
           case 2: price=2.5;  break;
           case 3: price=4.0;  break;
           case 4: price=3.5;  break;
           default: price=0.0;  break;
        }
        printf("price = %0.1f\n", price);  
    }
    printf("Thanks \n");
   
}

同意.

你的for()循环了五次啊

用它  吃掉回车....

#include <stdio.h>
int main(void)
{
    int choice, i;   double price;
    for( i = 1; i <= 5; i++)
    {   
        printf("[1] Select crisps \n");
        printf("[2] Select popcorn \n");
        printf("[3] Select chocolate \n");
        printf("[4] Select cola \n");
        printf("[0] exit \n");
        printf("Enter choice: ");
        scanf("%d", &choice);   
        getchar();
        switch (choice)
        {         
        case 1: price=3.0;  break;
        case 2: price=2.5;  break;
        case 3: price=4.0;  break;
        case 4: price=3.5;  break;
        default: price=0.0;  break;
        }
        printf("price = %0.1f\n", price);  
    }
    printf("Thanks \n");
    return 0;                                    //int 型要加这个的....既有返回
}

scanf  有很多陷阱  当你第一个字符输入类型不符合的时候  
scanf  就会把它丢弃  取得默认值  -858993460
就会输出0.000  scanf 还会继续丢弃  至于为什么 我也不知道了