Introduction to C Language

What is C?

C is a procedural, structured, general-purpose programming language known for its:

• Speed and performance
• Efficiency and low-level memory control
• Portability across operating systems
• Ability to interact with hardware

C is often called the "Mother of All Modern Languages" because so many languages were created using it or inspired by it.

A Brief History of C

• 1960s – Developed from earlier languages like BCPL and B.
• 1972 – Dennis Ritchie created C at Bell Labs for building the UNIX OS.
• 1978 – Brian Kernighan & Dennis Ritchie published "The C Programming Language (K&R C)".
• 1989 – ANSI standardized C → ANSI C / C89.
• 1990 – ISO adopted the standard as C90.
• 1999 – C99 introduced new features like inline, long long, variable-length arrays.
• 2011 – C11 added multi-threading support and safety features.

Why Should You Learn C?

• Strong foundation for advanced languages like C++, Java, Python, Go, Rust
• Used in systems programming and OS development (Linux, Windows kernels)
• Used in embedded systems (microcontrollers, IoT)
• Helps understand memory, pointers, and low-level internals
• Portable across different platforms (Write once, compile anywhere)
• High-performance applications need C

Key Features of C

• Fast & Efficient – No heavy runtime or garbage collector
• Structured Programming – Ensures clean, modular code
• Rich Library – Standard library provides many functions
• Portable Code – Works on almost any system
• Mid-Level Language – Both high-level and low-level capabilities
• Dynamic Memory Management – malloc(), calloc(), realloc(), free()
• Hardware-level Access – Through pointers and address manipulation

How C Works Internally?

C program compilation follows 4 main stages:

C Source Code (.c)
       ↓
Preprocessor (includes, macros)
       ↓
Compiler (converts to assembly)
       ↓
Assembler (creates object files)
       ↓
Linker (links all object files + libraries)
       ↓
Executable File (.exe / .out)

• Compiler → Translates code to machine-level instructions
• Linker → Combines code + libraries
• Loader → Loads program into memory for execution

Applications of C

• Operating Systems (Linux Kernel, Windows NT)
• Compilers (GCC, Clang)
• Databases (MySQL, Oracle components)
• Embedded Systems (Arduino, microcontrollers)
• Game Engines
• Network Programming & Socket Programming
• System Utilities (Command-line tools)

Your First C Program

#include <stdio.h>

int main() {
    printf("Hello, World!");
    return 0;
}

Explanation of the Program

• #include <stdio.h> → Standard Input Output Library
• main() → Entry point of every C program
• printf() → Outputs text to the screen
• return 0; → Ends program safely

Advantages of C

• Extremely fast execution
• Supports modular programming
• Direct interaction with memory via pointers
• Best for system software
• Huge community and documentation
• Portable across different platforms

Limitations of C

• No built-in object-oriented features
• No garbage collection
• Manual memory management → risk of memory leaks
• Unsafe operations may crash the program

Practice Questions

1. Explain the history and evolution of C.
2. What are the main features of C?
3. Write advantages and limitations of C.
4. Explain the C compilation process.
5. Write a C program to print your details.

Practice Task

#include <stdio.h>

int main() {
    printf("Name: Your Name\n");
    printf("Age: Your Age\n");
    printf("Course: C Programming\n");
    printf("Goal: Become a Software Engineer\n");
    return 0;
}