c - 在我提示用户继续后，它以某种方式跳过我的键盘缓冲区，让我输入我想要的任何内容

Question

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已关闭 5 年前。

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

void buffer();

int fib(int x, int y) {
    if (y <= 1) {
        return x;
    } else {
        return fib(x, y - 1) + fib(x, y - 2);
    }
}

int main(int argc, char * argv[]) {
    int x;
    int y;
    char answer = 'y';

    while (answer == 'y') {
        printf("Please enter the initial value of the green curd: ");
        scanf("%d", &x);
        buffer();

        while (x < 1) {
            printf("I'm sorry that value is unrecognized or is negative.\n");
            printf("Please enter the initial value of the green curd: ");
            scanf("%d", &x);
            buffer();
        }

        printf("Please enter the number of days: ");
        scanf("%d", &y);
        buffer();

        while (y < 1) {
            printf("I'm sorry that value is unrecognized or is negative.\n");
            printf("Please enter the number of days: ");
            scanf("%d", &y);
            buffer();
        } 

        printf("With the initial population of %d pounds of crud growing for %d days.\n", x, y);
        printf("The final population would be %d pounds.\n", fib(x, y / 5));
        printf("Would you like to continue? (y/n): ");
        scanf("%c", &answer);
        buffer();

        while (answer != 'y') {
            if (answer == 'n') {
                exit(1);
            }

            printf("I'm sorry that value is unrecognized or is negative.\n");
            printf("Would you like to continue? (y/n): ");
            scanf("%c", &answer);
            buffer();   
        }        
    }

    return 0
}

 void buffer(void) {
     char ch;
     scanf("%c", &ch);

     while (ch != '\n') {
         scanf("%c", &ch);
     }
 }

我有一个项目要交到学校。只是寻求一些建议。程序运行良好，但是当我决定继续时，缓冲区语句不会阻止我第二次输入字符。只有当我到达末尾继续时，程序实际上使用我的 while 循环来停止任何无效输入。

Answer 1

scanf("%d", &y);

将换行符保留在输入缓冲区中，然后立即由以下内容拾取

scanf("%c", &answer);

您应该让 scanf() 通过在格式字符串前插入一个空格来跳过空格，其中包括换行符

scanf(" %c", &answer);