### 3.3 Compiling C++ Programs

C++ source files conventionally use one of the suffixes ‘`.C`’, ‘`.cc`’, ‘`.cpp`’, ‘`.CPP`’, ‘`.c++`’, ‘`.cp`’, or ‘`.cxx`’; C++ header files often use ‘`.hh`’, ‘`.hpp`’, ‘`.H`’, or (for shared template code) ‘`.tcc`’; and preprocessed C++ files use the suffix ‘`.ii`’. GCC recognizes files with these names and compiles them as C++ programs even if you call the compiler the same way as for compiling C programs (usually with the name `gcc`).

However, the use of `gcc` does not add the C++ library. `g++` is a program that calls GCC and automatically specifies linking against the C++ library. It treats ‘`.c`’, ‘`.h`’ and ‘`.i`’ files as C++ source files instead of C source files unless `-x` is used. This program is also useful when precompiling a C header file with a ‘`.h`’ extension for use in C++ compilations. On many systems, `g++` is also installed with the name `c++`.

When you compile C++ programs, you may specify many of the same command-line options that you use for compiling programs in any language; or command-line options meaningful for C and related languages; or options that are meaningful only for C++ programs. See Options Controlling C Dialect, for explanations of options for languages related to C. See Options Controlling C++ Dialect, for explanations of options that are meaningful only for C++ programs.