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:
![](https://img-blog.csdnimg.cn/20190215115814994.png?x-oss-process=image/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]#
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