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C Programming Tutorial for Beginners

Introduction to C

C is a powerful, general-purpose programming language developed by Dennis Ritchie in 1972. It is widely used for system programming, embedded systems, game development, and more.

Why Learn C?

✅ Foundation for other languages (C++, Java, Python)
✅ High performance & efficiency
✅ Low-level memory access
✅ Used in operating systems (Linux, Windows) and embedded systems

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1. Setting Up a C Environment

Install a C Compiler

• Windows: Install MinGW or use Visual Studio with C support.

• Linux/macOS: Use gcc (usually pre-installed).

Writing Your First C Program

Create a file named hello.c:

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#include <stdio.h>  // Standard Input/Output library

int main() {        // Main function (entry point)
    printf("Hello, World!\n");  // Print to console
    return 0;       // Exit program successfully
}

Compiling & Running

• Windows (Command Prompt)

  sh

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  gcc hello.c -o hello
  hello.exe

• Linux/macOS (Terminal)

  sh

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  gcc hello.c -o hello
  ./hello

Output:

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Hello, World!

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2. Basic C Syntax

Variables & Data Types

Data Type	Example	Description
int	int x = 10;	Integer
float	float pi = 3.14;	Floating-point number
char	char letter = 'A';	Single character
double	double bigNum = 12345.6789;	High-precision float

Input & Output

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#include <stdio.h>

int main() {
    int age;
    printf("Enter your age: ");
    scanf("%d", &age);  // Read input
    printf("You are %d years old.\n", age);
    return 0;
}

Operators

• Arithmetic: +, -, *, /, % (modulus)

• Comparison: ==, !=, >, <, >=, <=

• Logical: && (AND), || (OR), ! (NOT)

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3. Control Structures

If-Else Statement

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int num = 10;
if (num > 0) {
    printf("Positive\n");
} else if (num < 0) {
    printf("Negative\n");
} else {
    printf("Zero\n");
}

Loops

• for Loop

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  for (int i = 0; i < 5; i++) {
      printf("%d ", i);  // Output: 0 1 2 3 4
  }

• while Loop

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  int i = 0;
  while (i < 5) {
      printf("%d ", i++);  // Output: 0 1 2 3 4
  }

Switch-Case

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int day = 3;
switch (day) {
    case 1: printf("Monday"); break;
    case 2: printf("Tuesday"); break;
    default: printf("Invalid day");
}

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4. Functions

Functions help in code reusability.

Example: Add Two Numbers

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#include <stdio.h>

// Function declaration
int add(int a, int b);

int main() {
    int result = add(5, 3);
    printf("Sum: %d\n", result);  // Output: 8
    return 0;
}

// Function definition
int add(int a, int b) {
    return a + b;
}

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5. Arrays & Strings

Arrays

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int numbers[5] = {1, 2, 3, 4, 5};
printf("%d", numbers[0]);  // Output: 1

Strings (Array of char)

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char name[] = "Alice";
printf("%s", name);  // Output: Alice

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6. Pointers (Basics)

Pointers store memory addresses.

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int x = 10;
int *ptr = &x;  // Pointer to x
printf("%d", *ptr);  // Output: 10 (value at address)

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7. Structures

Structures group related data.

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struct Person {
    char name[50];
    int age;
};

int main() {
    struct Person p1 = {"John", 25};
    printf("Name: %s, Age: %d", p1.name, p1.age);
    return 0;
}

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8. File Handling

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#include <stdio.h>

int main() {
    FILE *file = fopen("test.txt", "w");  // Open in write mode
    fprintf(file, "Hello, File!");  // Write to file
    fclose(file);  // Close file
    return 0;
}