Apprendre What is CMake? | Getting Started with CMake

Definition

CMake is a cross-platform build system generator that uses configuration files (CMakeLists.txt) to describe how a project should be built and then generates native build files for compiling the source code on different operating systems and compilers.

CMake does not compile programs by itself. Instead, it describes how your program should be built, and then generates the correct build files for your operating system and compiler. To make this concrete, look at a very simple C program and see how both a Makefile and a CMakeLists.txt file can be used to build it. The goal is the same, compile main.c into an executable, but the way each system approaches the task is very different.

main.c

CMakeLists.txt

Makefile.


              123456
            
#include <stdio.h>

int main() {
    printf("Hello, world!\n");
    return 0;
}

The Makefile and CMakeLists.txt both define how to build a C program from main.c, but they work differently. A Makefile directly calls the compiler using shell commands and often needs manual changes for different platforms. In contrast, CMakeLists.txt uses a declarative approach, you describe what to build, and CMake generates the correct build files for your system. This makes projects easier to maintain and more portable across platforms.

main.c

CMakeLists.txt


              123456789101112
            
#include <stdio.h>

int main() {
#ifdef PLATFORM_WINDOWS
    printf("Hello from Windows!\n");
#elif defined(PLATFORM_LINUX)
    printf("Hello from Linux!\n");
#else
    printf("Hello from an unknown platform!\n");
#endif
    return 0;
}

CMake allows your project to automatically adjust to different operating systems such as Windows and Linux. By using platform checks like WIN32 and UNIX, it applies platform-specific settings during compilation, making your application portable without changing build instructions. To better understand how CMake improves the build process compared to traditional Makefiles, see the comparison below:

After comparing both approaches, it becomes clear that build systems automate the process of compiling source code into executables. While Makefiles were widely used in the past, they become harder to manage as projects grow. CMake simplifies development by generating native build files for each platform from a single configuration, making modern C/C++ projects easier to scale, maintain, and extend.

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Section 1. Chapitre 1

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Definition

main.c

CMakeLists.txt

Makefile.


              123456
            
#include <stdio.h>

int main() {
    printf("Hello, world!\n");
    return 0;
}

main.c

CMakeLists.txt


              123456789101112
            
#include <stdio.h>

int main() {
#ifdef PLATFORM_WINDOWS
    printf("Hello from Windows!\n");
#elif defined(PLATFORM_LINUX)
    printf("Hello from Linux!\n");
#else
    printf("Hello from an unknown platform!\n");
#endif
    return 0;
}

Tout était clair ?

Merci pour vos commentaires !

Section 1. Chapitre 1