scanf 在 C 中不能正常工作 [英] scanf not working well in C

问题描述

    if (a % 5)
            goto ask;
            else
            goto main;

ask:printf("Do You Want To Exit ? Y \\ N . . . \n");
        scanf("%c", &YN);
        getch();
        if (YN == 'Y')
        {
y:          system("cls");
            YN = 1;
            goto sign;
        }
        else if (YN == 'y')
            goto y;
        else if (YN == 'N')
        {
n:          system("cls");
            YN = 0;
            goto sign;
        }
        else if (YN == 'n')
        {
            goto n;
        }
        else
        {
            printf("Sorry ..Didn't Catch that ... ");
                goto ask;
        }

有人帮助我了解我的问题出于某种原因，我从这段代码中得到的输出是你想退出 y\n 吗?"获取...抱歉没听清你想退出 y\n 吗?"

someone help me understand my problem for somereason the output I get from this code is "Do u want to exit y\n ?" getchar ... "sorry didnt catch that do u want to exit y\n ? "

好像是第一次跳过了scanf()，程序直接跳到了else ==> 抱歉我没搞定那个"并且只有在第二次才知道如何使用 scanf().

It looks like it jumped over the scanf() for the first time and the program went directly to the else ==> "sorry i didnt get that" and only in the second time it fiugres out how to use the scanf().

推荐答案

scanf() 使用 %c 读取字符，是的，ENTER 按键 [在您之前的输入之后] 对于 %c 几乎有效 [检查下面的剧透].

scanf() reads characters with %c and yes, the ENTER key press [after your previous input] is pretty much vaild for %c [Check the below spoiler].

ENTER 键按下 == 换行

ENTER key press == newline

使用

scanf(" %c", &YN);  //mind the space brefore `%c`
       ^
       |

忽略任何先前存储的[也，前导]空格[包括换行符.]

to ignore any previously-stored [also, leading] whitespace [including a newline.]

^{注意:这也消除了对 getch();}

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