The difference between GCC and g++

When we compiled C + + code, some people use GCC, some people use g++, so all kinds of statements come, such as C code with GCC, and C + + code with g++, or compiled with GCC, link with g++, for a moment I do not know which statement is correct, if you encounter the last extern "C", There are more differences, and here I want to finish, after all, the purpose of knowledge is to be more sober, not more confused.
Myth One: gcc can only compile C code, g++ can only compile C + + code

Both are possible, but please note:
1. The suffix is. C, GCC treats it as a C program, and g++ as a C + + program; the suffix is. cpp, both of which are considered C + + programs, note that although C + + is a superset of C, there are different requirements for syntax, such as:
#include <stdio.h>
int main (int argc, char* argv[]) {
if (argv = = 0) return;
Printstring (argv);
return;
}
int printstring (char* string) {
sprintf (String, "This is a test.\n");
}
If you follow the grammar rules of C, OK, no problem, but once the suffix is changed to CPP, three errors are reported immediately: "Printstring undefined";
"Cannot convert ' char** ' to ' char*";
"Return-statement with no value";
Corresponds to the part of the previous red callout, respectively. Visual C + + syntax rules are more rigorous.
2. During the compile phase, g++ calls GCC, which is equivalent to C + + code, but because the GCC command is not automatically linked to the libraries used by C + + programs, it is usually done with g++ to complete the link, for the sake of unification, simply compile/link all with g++, which gives an illusion, As if the CPP program can only be used g++.

Myth Two: GCC does not define __cplusplus macros, and g++ will

In fact, this macro simply indicates that the compiler will interpret the code in C or C + + syntax, as described above, if the suffix is. c, and the GCC compiler is used, the macro is undefined, otherwise it is defined.

Myth Three: Compile only with GCC, link only with g++
Strictly speaking, this sentence is not wrong, but it confuses the concept,This should be said: Compile can be used gcc/g++, and links can be used g++ or gcc-lstdc++。 Because GCC commands are not automatically joined to libraries that are used by C + + programs, you typically use g++ to complete joins. In the compilation phase, however, g++ automatically calls GCC, which is equivalent.

Myth four: extern "C" has relation with gcc/g++

In fact, no matter whether it is GCC or g++, with the extern "C", all are named in C to the symbol, otherwise, are named in C + +. The test is as follows:
me.h：
extern "C" void cppprintf (void);

Me.cpp:
#include <iostream>
#include "me.h"
using namespace Std;
void cppprintf (void)
{
cout << "hello\n";
}

Test.cpp:
#include <stdlib.h>
#include <stdio.h>
#include "me.h"
int main (void)
{
Cppprintf ();
return 0;
}

1. First add extern "C" to me.h, see what is different with GCC and g++ naming

[Email protected] g++]# g++-S Me.cpp
[email protected] g++]# less ME.S
. GLOBL _Z9CPPPRINTFV//Note the naming of this function
. Type cppprintf, @function
[Email protected] gcc]# gcc-s me.cpp
[email protected] gcc]# less ME.S
. GLOBL _Z9CPPPRINTFV//Note the naming of this function
. Type cppprintf, @function
Exactly the same!

2. Remove the extern "C" in the me.h to see what is different with GCC and g++ naming
[Email protected] gcc]# gcc-s me.cpp
[email protected] gcc]# less ME.S
. GLOBL _Z9CPPPRINTFV//Note the naming of this function
. Type _Z9CPPPRINTFV, @function
[Email protected] g++]# g++-S Me.cpp
[email protected] g++]# less ME.S
. GLOBL _Z9CPPPRINTFV//Note the naming of this function
. Type _Z9CPPPRINTFV, @function
Exactly the same!
"Conclusion" is identical, it can be seen that extern "C" is not related to the adoption of gcc/g++, the above test also indirectly confirms the previous saying: In the compilation phase, g++ is called GCC.

The difference between GCC and g++