scanf函数/ getchar函数正常工作只有第一次通过循环？ [英] scanf/getchar working correctly only first time through loop?

问题描述

我试图让用户在一些他们想要进入的次数（并为每个号码的链表节点）。

I'm trying to have the user enter in a number as many times as they want (and create a linked list node for each of the numbers).

清除文字输入缓冲器，但无济于事不过，我试过多种方法。奇怪的是，code将通过执行一次，但不能正确地执行第二。

However, I've tried multiple method of clearing the character input buffer but to no avail. Strangely, the code will execute once through but not execute correctly the second.

例如，与下面的code，终端读取：

For example, with the code below, the terminal reads:

would you like to enter an integer?
y
Enter an integer: 4
would you like to enter an integer?
y
**program terminates**

和我使用 scanf函数（％C，YESNO）时前; 我甚至不能够输入Y的最后一行。它只是终止。

And before when I was using scanf("%c", yesno); I would not even be able to input 'y' on the last line. It just terminated.

struct node *read_numbers(void){
    struct node *first = NULL;
    int n; char yesno;
    yesno = 'y';
    while( yesno == 'y'){
        printf("Would you like enter an integer ((y) for yes/(n) for no):\n");
        yesno = getchar();  
        while(getchar() != '\n');
        if(yesno == 'y'){
            printf("Enter an Integer:");
            scanf(" %d", &n);
            first = add_to_list(first, n);
            } else {
                return first;
                }
        } // end while
    }

我在文字输入和缓冲区读取了，按说的getchar（）方法应该工作。我在使用它错了吗？我也试过scanf（）函数与％C前后多余的空格，但无济于事。

I read up on character inputs and buffers, and supposedly the getchar() method should work. Am I utilizing it wrong? I've also tried scanf() with extra spaces before and after the "%c", but to no avail.

推荐答案

您需要scanf函数后消化换行符。你可以做你的code上面做什么：

You need to digest the newline after the scanf. You can do what you're doing above in the code:

scanf(" %d", &n);
while(getchar() != '\n');
first = add_to_list(first, n);

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