CMake: Building Like a Professional

Why not just long g++ commands?

g++ main.cpp math_utils.cpp ... -o app does not scale: 40 files, include paths, libraries, Debug/Release flags. CMake describes the project once; it generates the right build commands for any platform.

The minimal honest CMakeLists.txt

cmake_minimum_required(VERSION 3.20)
project(finance LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable(finance
    src/main.cpp
    src/ledger.cpp
    src/report.cpp
)

target_compile_options(finance PRIVATE -Wall -Wextra -Wpedantic)

Read it as a sentence: "a project named finance, C++20, one executable target finance from these sources, with warnings on for this target."

• Target is the unit of everything: an executable or a library, its sources, its flags, its dependencies.
• PRIVATE means the flags apply to building this target only.

The two-command build (memorize these)

cmake -B build            # configure: read CMakeLists, generate build files into build/
cmake --build build       # build: compile + link via the generated system
./build/finance           # run

-B build keeps all generated files in one directory (git-ignored — module 17). Re-run configure after editing CMakeLists; re-run build after editing code — it recompiles only what changed.

Debug vs Release

cmake -B build-debug -DCMAKE_BUILD_TYPE=Debug      # -g, no optimization: debuggable
cmake -B build-release -DCMAKE_BUILD_TYPE=Release  # -O2: fast, unreadable in a debugger

Debug while developing; release when measuring or shipping. (Sanitizers attach to the Debug build — Intermediate territory, name-checked here.)

What Beginner CMake is NOT

No custom functions, no package hunting (find_package), no install rules. When a project needs those, it has outgrown Beginner — and now it has the vocabulary to say so.