为什么每次使用malloc时都会收到警告？ [英] Why do I get a warning every time I use malloc?

问题描述

  int * x = malloc（sizeof（int））; 
  

我从 gcc ：

new.c：7：warning：隐式声明函数'malloc'

new.c：7：warning ：不兼容的隐式声明内置函数'malloc'

解决方案

您需要添加：

  #include< stdlib.h> 
  

该文件包含内置函数 malloc 。如果你不这样做，编译器认为你想定义自己的函数名为 malloc ，它会提醒你，因为：

1. 您没有明确地声明它和


2. 已经有一个内置函数，与隐式声明不同的签名（当函数被隐式声明时，其返回值和参数类型假定为 int ，这与内置函数不兼容-in malloc ，它需要一个 size_t 并返回一个 void * ）。

If I use malloc in my code:

int *x = malloc(sizeof(int));

I get this warning from gcc:

new.c:7: warning: implicit declaration of function ‘malloc’
new.c:7: warning: incompatible implicit declaration of built-in function ‘malloc’

解决方案

You need to add:

#include <stdlib.h>

This file includes the declaration for the built-in function malloc. If you don't do that, the compiler thinks you want to define your own function named malloc and it warns you because:

1. You don't explicitly declare it and
2. There already is a built-in function by that name which has a different signature than the one that was implicitly declared (when a function is declared implicitly, its return and argument types are assumed to be int, which isn't compatible with the built-in malloc, which takes a size_t and returns a void*).

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