c 删除新行字符帮助

发布于 2024-10-07 17:52:33 字数 373 浏览 4 评论 0原文

我对 c 很陌生，如果这是一个愚蠢的问题，我很抱歉！

我有这个：

  fgets(question,200,stdin);
  char *memq = malloc(sizeof(strlen(question)));
  memq= question;

但是问题变量的末尾总是有一个新行！我该如何删除它/防止它发生？

我试过了：

  fgets(question,200,stdin);
  char *memq = malloc(sizeof(strlen(question))-sizeof(char));
  memq= question;

没有效果！

原文

Im fairly new to c sorry if this is a stupid question!

i have this:

  fgets(question,200,stdin);
  char *memq = malloc(sizeof(strlen(question)));
  memq= question;

however the question variable always has a new line on the end of it !
how do i remove this / prevent it happening?

i have tried this:

  fgets(question,200,stdin);
  char *memq = malloc(sizeof(strlen(question))-sizeof(char));
  memq= question;

there was no effect!

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ゞ花落谁相伴 2024-10-14 17:52:33

要摆脱换行符，在 malloc 之前，执行 :

question[strlen(question)-1] = 0;

另一种选择（在下面的评论中建议）将执行以下操作：

question[strcspn(question, "\n")] = '\0';

将 malloc 行更改为：

char *memq = malloc(strlen(question)+1);

将分配行更改

memq = question;

为：

strcpy (memq, question);

to get rid of the newline, before your malloc, do :

question[strlen(question)-1] = 0;

an alternative (suggested in the comments below) would be to do the following instead:

question[strcspn(question, "\n")] = '\0';

change the malloc line to:

char *memq = malloc(strlen(question)+1);

change the assignation line:

memq = question;

to:

strcpy (memq, question);

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请你别敷衍 2024-10-14 17:52:33

这段代码被严重破坏了。

如果您打算将数据复制到 memq 中，则需要在其中分配 strlen+1 字节（为什么要执行 sizeof？这将分配 4 个字节）字节，因为 sizeof(strlen()) 是 sizeof(int))。

您不能只是将 question 分配给 memq 并期望将数据复制进去。这一切都会覆盖您刚刚 malloc 编入的指针memq，泄漏它。你必须这样做

strcpy(memq, question);

这就是为什么你需要在memq中额外的字节，因为这包括一个空终止符。此时，您可以从 memq 中删除换行符，如其他地方所述。

This code is badly broken.

You need to allocate strlen+1 bytes into memq if you plan to copy the data there (why are you doing sizeof? that will allocate 4 bytes since sizeof(strlen()) is sizeof(int)).

You cannot just assign question to memq and expect the data to be copied in. All this does is overwrite the pointer you just malloc-ed into memq, leaking it. You have to do

strcpy(memq, question);

That's why you need the extra byte in memq, since this includes a null terminator. At this point you are in position to remove the newline from memq as noted elsewhere.

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