c - Linux C : error of redefinition of in include headers

Question

我有一个项目，它有下面的标题包括 map :

main.c <- main.h <- tcphelper.h <- tcptest.h <- util.h
                 <- udptest.h    <------------- util.h

在util.h中，我定义了一个struct cpu_usage的函数原型(prototype):

void get_cpu_usage(struct cpu_usage *cu);

现在当我用GCC编译这个项目时，我有这个重定义错误。如何解决这个问题？

谢谢!

In file included from udptest.h:15:0,
                 from main.h:10,
                 from main.c:7:
util.h:27:8: error: redefinition of struct cpu_usage
 struct cpu_usage{
        ^
In file included from tcptest.h:14:0,
                 from tcphelper.h:10,
                 from main.h:9,
                 from main.c:7:
util.h:27:8: note: originally defined here
 struct cpu_usage{
        ^

Answer 1

您需要添加 Include guards到您的头文件，以防止多次包含它们的内容。示例:

#ifndef UTIL_H_INCLUDED
#define UTIL_H_INCLUDED

/* header contents goes here */

#endif /* UTIL_H_INCLUDED */