What is the difference between g++ and gcc compilers

• Why use g++ instead of gcc?
• Why some codes compile with g++ but not in gcc?
• How do we know what compiler works fine with our code?

1. Background of gcc and g++ compilers

gcc / g++ is just a front-end driver programs which invokes the actual compiler and / or linker based on the options given to it.

If you invoke the compiler as gcc:

• it will compile as C or C++ based on the file extension (.c, or .cc / .cpp);
• it will link as C, i.e. it will not pull in C++ libraries unless you specifically add additional arguments to do so.

If you invoke the compiler as g++:

• it will compile as C++ regardless of whether or not the file extension is .c or .cc / .cpp;
• it will link as C++, i.e. automatically pull in the standard C++ libraries.

 

2. Examples you may face the difference between g++ and gcc

$ gcc -o test test.c

$ g++ -o test test.c

This will compile with gcc, but not with g++ and give some errors. C++ requires an explicit cast from void* here, whereas C does not.

This will give errors when compile using gcc. (because of ‘int array’ – it is not recognized in c linking stage)

we can prove it by compiling using gcc and then linking with g++

$ gcc –c test.c

$ g++ –o test test.o

$ ./test

• Where as g++ not compile .c ass plain C, it always compiles as c++.
• g++ automatically links the C++ runtime library where gcc doesn't.