C无限do while循环

Question

这是一个类的简单程序，它以分钟为单位提示用户他或她淋浴的时间长度（作为正整数，根据需要重新提示），然后打印同等数量的水瓶（作为整数）。

假设淋浴器每分钟使用1.5加仑水（192盎司），塑料瓶大小为16盎司

我的do-while循环成功地拒绝了负数和0，但是，如果我输入“foo”这样的文本，当提示输入淋浴的长度（以分钟为单位）时，程序将进入无限循环，永远运行该循环并打印“How long is your shower（以分钟为单位）？”

有没有办法改进while条件来避免这种情况？

#include <stdio.h>

int min_to_bottles(int *n);

int main(void)
{
    int minutes;
    int bottles;
    do
    {
        printf("How long is your shower(in minutes)?:");
        scanf("%i", &minutes);
    }
    while (minutes < 1);

    bottles = min_to_bottles(&minutes);

    printf("Equivalent of bottles used per shower is: %i\n", bottles);

}

int min_to_bottles(int *n)
{
    int bottles;
    int oz = 192 * *n;
    bottles = oz/16;
    return bottles;
}

Answer 1

始终检查scanf()的返回值：

int result;
do {
    printf("How long is your shower(in minutes)?:");
    result = scanf("%d", &minutes);
    if(result != 1) 
        break;
} while (minutes < 1);

较短的版本（如果只需要一次扫描）：

printf("How long is your shower(in minutes)?:");

while ((scanf("%d", &minutes) == 1) && (minutes < 1))
    ;

在int min_to_bottles(int*n)；中不需要使用指针作为参数：

#include <stdio.h>

int min_to_bottles(int n)
{
    return (192 * n) / 16;
}

int main(void)
{
    int minutes = 0;
    int bottles = 0;

    printf("How long is your shower(in minutes)?: ");

    while ((scanf("%d", &minutes) == 1) && (minutes < 1 || minutes > 100))
        printf("Enter a number between 1 and 100 : ");

    // if(minutes == 0) here means invalid data was entered.
    //    so a check could be done before continuing.

    bottles = min_to_bottles(minutes);

    printf("Equivalent of bottles used per shower is: %d\n", bottles);

    return 0;
}