隐式声明“获取" [英] Implicit declaration of 'gets'

问题描述

我了解到隐式声明"通常意味着必须在调用函数之前将其置于程序的顶部，否则我需要声明原型.
但是，gets应该在stdio.h文件中(该文件已包括在内).
有什么办法可以解决这个问题?

I understand that an 'implicit declaration' usually means that the function must be placed at the top of the program before calling it or that I need to declare the prototype.
However, gets should be in the stdio.h files (which I have included).
Is there any way to fix this?

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
   char ch, file_name[25];
   FILE *fp;

   printf("Enter the name of file you wish to see\n");
   gets(file_name);
   fp = fopen(file_name,"r"); // read mode
   if( fp == NULL )
   {
      perror("Error while opening the file.\n");
      exit(EXIT_FAILURE);
   }
}

推荐答案

您是对的，如果包含适当的标头，则不应收到隐式声明警告.

You are right that if you include proper headers, you shouldn't get the implicit declaration warning.

但是，功能gets()已从C11标准中删除 .这意味着<stdio.h>中不再有gets()的原型. gets() 以前用于<stdio.h>.

However, the function gets() has been removed from C11 standard. That means there's no longer a prototype for gets() in <stdio.h>. gets() used to be in <stdio.h>.

删除gets()的原因是众所周知的:它不能防止缓冲区溢出.因此，您永远不要使用gets()并使用 fgets() 代替，并注意结尾的换行符(如果有).

The reason for the removal of gets() is quite well known: It can't protect against the buffer overrun. As such, you should never use gets() and use fgets() instead and take care of the trailing newline, if any.

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