c - 如何减少多个输出

Question

当我输入多个字符时，如何将输出限制为仅一个响应。

#include <stdio.h>
main(){
    char answer;

    printf("Do you want to continue(Y/N)?");
    scanf("%c", &answer);

    while ((answer != 'Y') && (answer != 'N')){
        printf("\nYou must type a Y or an N\n");
        printf("Do you want to continue(Y/N) ?");
        scanf(" %c", &answer);
    }
    return 0;
}

Answer 1

使用 getchar() 读取第一个字符，然后读取下一个字符，直到 EOF。

此外，循环外部(之前)的读取是不必要的。

#include <stdio.h>

// additional function for reading remaining input
void flush();

main(){

    // answer needs to be int, because getchar() can return -1 in case of EOF
    int answer; 

    while (1) {

        printf("Do you want to continue(Y/N)? ");
        answer = getchar();

        // read and ignore the remaining input
        flush();

        if ((answer == 'Y') || (answer == 'N'))
            break; // exit loop

        printf("\nYou must type a Y or an N\n");
    }

    // here answer contains 'Y' or 'N'
    // do what you need with this...

    return 0;
}

// function for consuming the remaining input
void flush()
{
    while (getchar() != EOF); // consume input until emptying
}