xx的c程序冲突类型错误和以前的xx隐式声明在这里 [英] Error in c programme conflicting types for xx and previous implicit declaration of xx was here

问题描述

假设我有一个定义了两个函数的文件insert.c：
1.insert_after
2.insert_before

定义这些func是这样的：

  insert_after（arg1）
 {
 if（condition 1）
 {.........} 
 else 
 insert_before（arg1）; 
 
 
 insert_before（arg）
 {
 if（条件1）
 {.........} 
 else 
 insert_after（arg）; 
} 
  

现在，如果此文件的insert.c包含在main.c和insert_after函数中被称为

 ＃includeinsert.c
 int main（）
 {
 insert_after（ARG）; 
返回0; 
} 
  

在使用gcc编译main.c时，遇到以下错误： p>

'insert_before'冲突类型

$ b 注意：以前的隐式声明'insert_before'在这里

这里有什么问题以及如何避免它？

解决方案

这是因为你没有为你的函数声明原型。默认情况下，没有原型的函数有一组未知的参数并返回一个int。但对于 insert_before 而言，情况并非如此。

创建一个文件 insert.h 您可以在其中声明它们：

  #ifndef INSERT_H 
 #define INSERT_H 
 
 void insert_before（type_of_arg）; 
 void insert_after（type_of_arg）; 
 
 #endif / * INSERT_H * / 
  

insert.c 。

您应该使用以下内容进行编译：

  gcc -Wall -Wstrict-prototypes -Wmissing-prototypes -o progname insert.c main.c 
  

Suppose I have a file insert.c in which two functions are defined: 1.insert_after 2.insert_before

The definitions of these func are something like this:

insert_after(arg1)
{ 
  if(condition 1)
    { ......... } 
  else
    insert_before(arg1); 
}

insert_before(arg)
{ 
  if(condition 1)
    { ......... } 
  else
    insert_after(arg); 
}

Now if this file insert.c is included in main.c and insert_after function is called

# include "insert.c"
int main()
{
  insert_after(arg);
  return 0;
}

On compiling main.c using gcc,the following error is encountered:

conflicting types for ‘insert_before’

note: previous implicit declaration of ‘insert_before’ was here

What is wrong here and how to avoid it?

解决方案

This is because you don't declare prototypes for your functions. A function which has no prototype, by default, has an unknown set of arguments and returns an int. But this is not the case for insert_before.

Create a file insert.h in which you declare them:

#ifndef INSERT_H
#define INSERT_H

void insert_before(type_of_arg);
void insert_after(type_of_arg);

#endif /* INSERT_H */

and include this file at the top of insert.c.

You should then compile with:

gcc -Wall -Wstrict-prototypes -Wmissing-prototypes -o progname insert.c main.c

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