Overview of C Language

Introduction

C is a powerful general-purpose programming language. It is fast, portable, and available on all platforms. C was developed in the early 1970s by Dennis Ritchie at Bell Labs and is still widely used today for system programming, creating operating systems, and other performance-critical applications.

History of C

The C programming language was originally developed for and implemented on the UNIX operating system by Dennis Ritchie. The language was derived from "B," which was created by Ken Thompson as a revision of the "BCPL" language. C has since become one of the most widely used programming languages of all time.

Features of C

C has several distinctive features:

• Simple and Efficient
• Rich Library
• Portability
• Extensible
• Middle-Level Language
• Memory Management
• Fast and Powerful

Basic Structure of a C Program

A simple C program consists of the following parts:

• Preprocessor Commands
• Functions
• Variables
• Statements & Expressions
• Comments

#include <stdio.h>

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

Compilation and Execution

To compile and execute a C program, follow these steps:

1. Write the code in a text editor and save with a .c extension, for example, hello.c
2. Open a terminal or command prompt
3. Navigate to the directory where the file is saved
4. Compile the program using a C compiler like GCC:
   gcc hello.c -o hello
5. Run the executable:
   ./hello

Data Types in C

C supports several built-in data types:

• int: Integer
• float: Floating-point number
• double: Double precision floating-point number
• char: Character
• void: Special purpose type

Control Structures

C provides several control structures:

• Decision Making: if, if...else, switch
• Loops: for, while, do...while
• Jump: break, continue, goto

Functions

Functions in C are used to divide the program into smaller parts. Each function performs a specific task. Here's an example of a function in C:

#include <stdio.h>

void greet() {
    printf("Hello from a function!\n");
}

int main() {
    greet();
    return 0;
}
                

Arrays

Arrays in C are used to store multiple values of the same type in a single variable. Here's an example:

#include <stdio.h>

int main() {
    int numbers[5] = {1, 2, 3, 4, 5};
    for(int i = 0; i < 5; i++) {
        printf("%d\n", numbers[i]);
    }
    return 0;
}
                

Pointers

Pointers in C are used to store the address of variables. They are a powerful feature of the language. Here's an example of using pointers:

#include <stdio.h>

int main() {
    int var = 20;
    int *ptr;
    ptr = &var;
    printf("Value of var: %d\n", var);
    printf("Address of var: %p\n", (void*)&var);
    printf("Value stored in ptr: %p\n", (void*)ptr);
    printf("Value pointed to by ptr: %d\n", *ptr);
    return 0;
}