C Compiler and Build Process

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A C compiler translates a C program written in high-level language into machine-level executable code.
The build process occurs in multiple stages.

Phases of C Compilation

The C build process consists of the following steps:

1. Preprocessing

2. Compilation

3. Assembly

4. Linking

1. Preprocessing

Handled by the preprocessor.

Tasks:

• Expands macros (#define)

• Includes header files (#include)

• Removes comments

• Handles conditional compilation

Output:

• Expanded source file (.i)

gcc -E program.c > program.i

2. Compilation

Handled by the compiler.

Tasks:

• Checks syntax

• Converts preprocessed code into assembly code

• Performs optimizations

Output:

• Assembly file (.s)

gcc -S program.i

3. Assembly

Handled by the assembler.

Tasks:

• Converts assembly code into machine code

Output:

• Object file (.o)

gcc -c program.s

4. Linking

Handled by the linker.

Tasks:

• Links object files

• Resolves external symbols

• Links standard libraries

• Creates final executable

Output:

• Executable file (a.out / program.exe)

gcc program.o -o program

Complete Build Command

gcc program.c -o program

Role of Header Files

• Provide function declarations

• Enable compiler to check function usage

#include 

Static vs Dynamic Linking

Compiler Errors vs Linker Errors

Compiler Errors

• Syntax errors

• Undeclared variables

Linker Errors

• Undefined reference

• Missing function definitions

Build Tools

• gcc – GNU Compiler Collection

• make – Build automation

• cmake – Build system generator

Summary

• C compilation occurs in multiple stages

• Preprocessor runs first

• Compiler generates assembly

• Assembler creates object code

• Linker produces executable