为什么一个printf语句之后的getchar（）读取的'\\ n'？ [英] Why is getchar() reading '\n' after a printf statement?

问题描述

我提示用户输入阵列的长度，初始化一个char []数组与该输入，然后提示用户键入消息进入焦炭[]数组。



我读了用户的消息的第一个字符用的getchar（）。



然而，的getchar（）读的是新线逃逸的'\\ n'正在读任何用户输入之前。它似乎越来越的'\\ n'从previous 的printf ，提示用户声明...




下面是相关code：

I'm prompting the user to enter the length of an array, initializing a char[] array with this input, and then prompting the user to type a message to enter into the char[] array.

I'm reading the first character of the user's message with getchar().

However, getchar() is reading the new-line escape '\n' before it is reading any user input. It seems to be getting '\n' from the previous printf statement that prompts the user...


Here is the relevant code:

#include <stdio.h>

int main(void) {

    int len = 0,
        originalLen = 0;

    printf("\n\nWhat is the length of the array? ");
    scanf("%d", &originalLen);
    char str[originalLen]; // intitializing the array

    printf("Enter a message to enter into the array: ");
    char target = getchar();
    str[len] = target;

    // why is getchar() reading '\n'?
    if (target == '\n') {
        printf("\n...what happened?\n");
    }
    return 0;
} // end of main

推荐答案

当你输入号码，然后按Enter键，数字和字符被放置在输入缓冲区中，他们分别是：

When you enter the number and hit the ENTER key, a number and a character are placed in the input buffer, they are namely:

• 输入的编号和


• 换行符（ \\ n ）。

• The entered number and
• The newline character(\n).

数字变由 scanf函数消耗，但换行保留在输入缓冲区，这是由读的getchar（）。

The number gets consumed by the scanf but the newline remains in the input buffer, which is read by getchar().

您需要使用消耗 \\ n 之前调用的getchar（）：

You need to consume the \n before calling getchar() by using:

scanf("%d ", &originalLen);
         ^^^

这告诉 scanf函数阅读次数和一个额外的性格，这是 \\ n 。

This tells scanf to read the number and an additional character, which is \n.

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