C Programming Basics for Beginners - Part I

 C is one of the most fundamental programming languages, widely used in system programming, embedded systems, and software development. Let's go through the basics of C programming step by step.

 1. Introduction to C Programming

C is a structured, procedural, and general-purpose programming language.

It was developed by Dennis Ritchie at Bell Labs in the 1970s.

Used in operating systems (Linux, Windows), game development, IoT, embedded systems, databases (MySQL), and more.

 

 2. Setting Up Your Environment

To write and run a C program, you need:

✅ Compiler: GCC (Linux/macOS), MinGW (Windows), Turbo C, Dev-C++, Code::Blocks, etc.
✅ Editor: VS Code, Code::Blocks, Notepad++, etc.
✅ IDE (Optional): Code::Blocks, Dev-C++ (for easy compilation).

3.  Structure of a C Program

A basic C program consists of:

 #include <stdio.h>  // Header file for input/output functions

int main() {  // Entry point of the program
    printf("Hello, World!\n");  // Output statement
    return 0;  // Indicates successful execution
}

Breakdown:

• #include <stdio.h> → Includes the standard input-output header file.
• int main() → Main function where execution starts.
• { } → Curly braces indicate the beginning and end of a function.
• printf("Hello, World!\n"); → Prints output to the screen.
• return 0; → Exits the program successfully.

4. Data Types in C

C supports different data types:

Type	Size (Bytes)	Example
int	4	int age = 25;
float	4	float pi = 3.14;
double	8	double price = 9.99;
char	1	char grade = 'A';
void	-	void function(); (No return)

 #include <stdio.h>

int main() {
    int age = 20;
    float height = 5.8;
    char grade = 'A';

    printf("Age: %d\n", age);
    printf("Height: %.2f\n", height);
    printf("Grade: %c\n", grade);

    return 0;
}

5. Variables and Constants

 A variable is a named memory location that holds data.

Syntax:

datatype variable_name = value;

int num = 10;
float pi = 3.14;

Constants

• A constant is a variable whose value cannot be changed.
• Using const keyword:
• const int MAX = 100;
  
  Using #define (Preprocessor Directive):
• #define PI 3.1415
   

6. Input & Output in C

 

Function	Purpose	Example

printf()

Displays output

printf("Hello!");

scanf()

Takes user input

scanf("%d", &num);

 Example Program: Taking User Input

 #include <stdio.h>

int main() {
    int age;
    printf("Enter your age: ");
    scanf("%d", &age);
    printf("You are %d years old.\n", age);
    return 0;
}
Note: & (Address-of Operator) is required in scanf() to store the input value in a variable.

 7. Operators in C

 

Operator                 Type	Example	Description

Arithmetic

+ - * / %

Addition, Subtraction, Multiplication, Division, Modulus

Relational

== != > < >= <=

Comparison operators

Logical

`&&

Bitwise

`&

^ ~ << >>`

Assignment

= += -= *= /=

Assign values

Increment/Decrement

++ --

Increase/Decrease by 1