为什么我的程序两次打印相同的语句？ [复制]

Question

我正在创建一个简单的应用程序来跟踪我的工作时间。用户输入他们正在做的工作的分钟数，程序将跟踪总数，直到终止。问题是在程序第一次运行之后，它会两次打印出它的第一条语句。我把它放在一个无限循环中，我对 scanf 和 printf 没有很好的掌握，所以我认为这就是我失败的地方。任何帮助将不胜感激。

这是程序的样子：

#include <stdlib.h>
#include <stdio.h>

void logic(int *minutesWorked, int *hoursWorked, int *totalMinutesWorked);

int main(void)
{
    int     minutesWorked = 0;
    int     hoursWorked = 0;
    char    letter = 0;
    int     totalMinutesWorked = 0;

    while (1) {
        printf("Enter I for input or T for total\n");
        scanf("%c", &letter);
        if (letter == 'i' || letter == 'I') {
            printf("Please enter minutes worked\n");
            scanf("%d", &minutesWorked);
            logic(&minutesWorked, &hoursWorked, &totalMinutesWorked);
        }
        else if (letter == 't' || letter == 'T') {
            printf("Hours worked is %d and minutes worked is %d\n", hoursWorked,totalMinutesWorked);
        }
    }
    return EXIT_SUCCESS;
}       /* ----------  end of function main  ---------- */


void    logic(int *minutesWorked, int *hoursWorked, int *totalMinutesWorked)
{
    *totalMinutesWorked += *minutesWorked;
    if (*totalMinutesWorked >= 60) {
        *hoursWorked += *totalMinutesWorked / 60;
        *totalMinutesWorked = *totalMinutesWorked % 60;
    }
}       /* -----  end of function logic  ----- */

这是它显示的示例：

Enter I for input or T for total
I
Please enter minutes worked
100
Enter I for input or T for total
Enter I for input or T for total
I
Please enter minutes worked
33
Enter I for input or T for total
Enter I for input or T for total
T
Hours worked is 2 and minutes worked is 13
Enter I for input or T for total
Enter I for input or T for total

Answer 1

最好的解决方案是使用 fgets() 而不是 scanf()，但如果这不是一个选项，您可以添加此行以在每次 scanf 调用后清除输入缓冲区：

fseek(stdin, 0, SEEK_END);