gcc编译c++文件

小咪咪 2022-03-19 05:24 322阅读 0赞

gcc是编译c语言的，默认情况下，如果直接编译c++程序，会报错：

\[root@server demo2\]\# ls  
hello.cpp  
\[root@server demo2\]\# cat hello.cpp   
\#include <iostream>  
using namespace std;  
int main()\{  
  cout<<"hello,c++"<<endl;  
  return 0;  
\}  
\[root@server demo2\]\# gcc -o hello hello.cpp   
/tmp/ccAa6oYP.o: In function \`main':  
hello.cpp:(.text+0xa): undefined reference to \`std::cout'  
hello.cpp:(.text+0xf): undefined reference to \`std::basic\_ostream<char, std::char\_traits<char> >& std::operator<< <std::char\_traits<char> >(std::basic\_ostream<char, std::char\_traits<char> >&, char const\*)'  
hello.cpp:(.text+0x14): undefined reference to \`std::basic\_ostream<char, std::char\_traits<char> >& std::endl<char, std::char\_traits<char> >(std::basic\_ostream<char, std::char\_traits<char> >&)'  
hello.cpp:(.text+0x1c): undefined reference to \`std::ostream::operator<<(std::ostream& (\*)(std::ostream&))'  
/tmp/ccAa6oYP.o: In function \`\_\_static\_initialization\_and\_destruction\_0(int, int)':  
hello.cpp:(.text+0x4a): undefined reference to \`std::ios\_base::Init::Init()'  
hello.cpp:(.text+0x59): undefined reference to \`std::ios\_base::Init::~Init()'  
collect2: error: ld returned 1 exit status

我们可以通过增加参数-lstdc++来编译，结果如下：

\[root@server demo2\]\# gcc -o hello hello.cpp -lstdc++  
\[root@server demo2\]\# ls  
hello  hello.cpp  
\[root@server demo2\]\# ./hello   
hello,c++  
\[root@server demo2\]\#   
如果编译c++程序，可以直接通过g++命令来编译，如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70][]

可以使用更简单的，直接g++ hello.cpp，这样生成的文件就是a.out

\[root@server demo2\]\# g++ hello.cpp   
\[root@server demo2\]\# ls  
a.out  hello.cpp  
\[root@server demo2\]\# ./a.out   
hello,c++  
\[root@server demo2\]\#

多个文件编译：准备circle.h,circle.cpp,main.cpp

circle.h

#ifndef CIRCLE_H
    #define CIRCLE_H
    class Circle{
      private:
        double r;
      public:
        Circle();
        Circle(double r);
        double area();
    };
    #endif

circle.cpp

#include "circle.h"
    Circle::Circle(){
       this->r = 5;
    }
    
    Circle::Circle(double r){
       this->r = r;
    }
    
    double Circle::area(){
       return 3.14*r*r;
    }

main.cpp

#include <iostream>
    #include "circle.h"
    using namespace std;
    
    int main(){
       Circle c(3);
       cout<<"area => "<<c.area()<<endl;
       return 0;
    }

多个文件编译，使用gcc编译，就类似这样：gcc -o main main.cpp circle.cpp -lstdc++，该命令编译中，文件不能带上circle.h头文件，否则会报错。

\[root@server demo1\]\# ls  
circle.cpp  circle.h  main.cpp  
\[root@server demo1\]\# gcc -o main main.cpp circle.cpp -lstdc++  
\[root@server demo1\]\# ls  
circle.cpp  circle.h  main  main.cpp  
\[root@server demo1\]\# ./main  
area => 28.26  
\[root@server demo1\]\#

使用g++编译：可以带上头文件circle.h

\[root@server demo1\]\# ls  
circle.cpp  circle.h  main.cpp  
\[root@server demo1\]\# g++ -o main2 main.cpp circle.h circle.cpp  
\[root@server demo1\]\# ls  
circle.cpp  circle.h  main2  main.cpp  
\[root@server demo1\]\# ./main2   
area => 28.26  
\[root@server demo1\]\#

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70]: /images/20220319/bde58790fb33489283f7664400143c0b.png