GCC/G++ Basics

Getting Started with g++

Installing GCC/G++ (Linux)

Install using your distribution's package manager.

sudo apt update
sudo apt install build-essential -y
// check versions
gcc --version
g++ --version

// CentOS / RHEL 7:
sudo yum groupinstall "Development Tools" -y
// CentOS Stream 8 / RHEL 8+ / Fedora:
sudo dnf groupinstall "Development Tools" -y

Installing GCC/G++ (Windows)

Download (URLs below) and add to your PATH environment variable so gcc/g++ commands work from any directory.

1. MinGW

https://osdn.net/projects/mingw/downloads/68260/mingw-get-setup.exe/

https://www.mingw-w64.org/downloads/ (recommended)

A gotcha with MinGW and the <thread> standard library:

Using threads with plain MinGW 9.2.0 requires these extra steps:

1. Download additional header files from this repository: https://github.com/meganz/mingw-std-threads

Place those header files into MinGW's include/ directory.

2. In your code, change #include <thread> to #include <mingw.thread.h> (as documented in the repository's README).
3. If compiling from the command line, add the flag -D_WIN32_WINNT=0x0501 to tell the compiler you are targeting Windows XP or later. (This may only be necessary for the win32 variant — the mingw-win64 version might not require it.)

The problematic version I used:

After switching to w64devkit:

Also note: plain MinGW requires you to separately install mingw32-make via the MinGW Installer (mingw-get.exe).

Basic g++ Usage Example

Create a text file (test.txt), rename its extension to .cpp (marking it as a C++ source file), open it with Notepad or VS Code, and write:

int main(){
    return 0;
}

Save and close the file.

Open a terminal (cmd) in the directory containing test.cpp and run:

g++ test.cpp

An a.exe executable appears in the current directory. Since no output name was specified, the compiler uses the default name a.

To specify the output file name with -o:

g++ -o b test.cpp

This produces b.exe in the current directory.

-o stands for output; the token immediately following it is the output filename. You can also reorder the arguments:

g++ test.cpp -o b

(Note: the -o flag and its value must stay together — do not separate them.)

C/C++ compilation consists of four stages (the commands above show the all-in-one shortcut):

Preprocessing → Compilation → Assembly → Linking

Preprocessing stage: .cpp → .i
Handles #include (header inclusion), #define (macro expansion), #ifdef (conditional compilation), and similar directives.

g++ -E test.cpp  // print preprocessed output (expanded macros and included headers) to the terminal
g++ -E test.cpp -o preprocess.i  // write output to preprocess.i

Compilation stage: .i → .s

Translates preprocessed code into assembly.

g++ -S preprocess.i -o assemble.s

Assembly stage: .s → .o

Converts assembly into machine code, producing an object file (not directly executable on its own).

g++ -c assemble.s -o machine.o
g++ -c test.cpp // you can also pass .cpp directly to generate the same-named .o

Linking stage: .o → .exe

Links one or more object files with libraries to produce an executable.

g++ machine.o -o test

Generating debug information:

g++ -g test.cpp -o test  // includes debug symbols compared to plain g++ test.cpp -o test

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