How to Compile C++ Program from Command Line Quickly

To compile a C++ program from the command line, use the g++ compiler followed by your source file name and the -o option to specify the output executable. For example, g++ program.cpp -o program compiles program.cpp into an executable named program.

Syntax

The basic command to compile a C++ program is:

• g++ source_file.cpp -o output_executable

Here:

• g++ is the C++ compiler command.
• source_file.cpp is your C++ source code file.
• -o tells the compiler to name the output executable.
• output_executable is the name you want for the compiled program.

bash

g++ source_file.cpp -o output_executable

Example

This example shows how to compile and run a simple C++ program that prints "Hello, world!".

cpp

#include <iostream>

int main() {
    std::cout << "Hello, world!" << std::endl;
    return 0;
}

Output

Hello, world!

Common Pitfalls

Common mistakes when compiling C++ programs include:

• Forgetting to specify the -o option, which results in an executable named a.out by default.
• Using the wrong file extension or misspelling the source file name.
• Not having g++ installed or not added to your system's PATH.
• Trying to run the source file instead of the compiled executable.

bash

/* Wrong: missing -o option, executable will be named a.out */
g++ program.cpp

/* Right: specify output executable name */
g++ program.cpp -o program

Quick Reference

Command	Description
g++ file.cpp	Compile file.cpp to default executable a.out
g++ file.cpp -o program	Compile file.cpp to executable named program
./program	Run the compiled executable named program
g++ -Wall file.cpp -o program	Compile with all warnings enabled
g++ -std=c++17 file.cpp -o program	Compile using C++17 standard

Key Takeaways

Use g++ source.cpp -o output to compile C++ programs from the command line.

The -o option sets the name of the output executable file.

If -o is omitted, the executable defaults to a.out.

Make sure g++ is installed and accessible in your system PATH.

Run your program by typing ./output on Unix or output.exe on Windows.