C+±–linux运行

1. 在linux下使用gcc/g++编译多个.h .c 文件

main.cpp :

#include <iostream>
#include <myhead.h>
using namespace std;
int main(){//fun_head();cout<<"in main"<<endl;int x=100;int y=200;cout<<"sum : "<<sum(x,y);return 0;
}

myhead.h

#ifndef __myhead_h
#define __muhead_h
void  print();
int sum(int a,int b);
#endif

myhead.cpp

#include "myhead.h"
#include <iostream>
using namespace std;
void  print(){cout<<"in fun head"<<endl;
}
int sum(int a,int b){return a+b;
}

如果直接编译：

>> g++ main.cpp -o main
main.cpp:2:20: fatal error: myhead.h: No such file or directory
compilation terminated.

通过 -I 选项 链接上去。重新编译:

>> g++ main.cpp -o main -I ../myinclude/
/tmp/ccH3BlLo.o: In function `main':
main.cpp:(.text+0x3e): undefined reference to `sum(int, int)'
collect2: error: ld returned 1 exit status

sum函数是在myhead.cpp文件上面定义的。也就是需要把myhead.cpp文件编译一下。

>> g++ -c myhead.cpp -o myhead.o

再次编译：

>> g++ main.cpp -o main -I ../myinclude/    ../myinclude/myhead.o

运行：

./main