gcc编译c++文件

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):