C Programming Tutorial

C is a foundational programming language used in many applications, from operating systems to embedded systems. This tutorial covers the basics of C programming with examples for each topic.

2. C Get Started

To get started, write your C code in a file with a .c extension. Then, compile it with a compiler like GCC. Example:

// hello.c
#include <stdio.h>

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

Compile and run with:

bash
gcc hello.c -o hello
./hello

3. C Syntax

C uses a structure where code blocks are enclosed in {} and statements end with ;. Example:

#include <stdio.h>

int main() {
    int number = 10;
    printf("The number is %d", number);
    return 0;
}

4. C Output

Use printf() from <stdio.h> to display output. Example:

printf("Hello, %s!", "Alice");

5. C Comments

Add comments to make code more understandable. Example:

// This is a single-line comment
/*
   This is a multi-line comment
*/

6. C Variables

Variables store data values. Example:

int age = 25;
float height = 5.9;
char grade = 'A';

7. C Data Types

Define data types for storing specific values. Example:

int age = 20;
float salary = 55000.50;
char letter = 'A';

8. C Constants

Use constants to store unchangeable values. Example:

const int PI = 3.1415;

9. C Operators

Operators perform operations on variables. Example:

int a = 5, b = 3;
int sum = a + b; // sum is 8

10. C Booleans

C uses integers for booleans (0 for false, non-zero for true). Example:

#include <stdbool.h>

bool isStudent = true;
if (isStudent) {
    printf("The person is a student.");
}

11. If…Else

The if...else statement controls conditional execution. Example:

int score = 85;
if (score >= 90) {
    printf("Grade: A");
} else if (score >= 80) {
    printf("Grade: B");
} else {
    printf("Grade: C");
}

12. Switch

The switch statement selects code to run based on matching cases. Example:

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

13. While Loop

A while loop repeats as long as the condition is true. Example:

int i = 1;
while (i <= 5) {
    printf("%d ", i);
    i++;
}

14. For Loop

A for loop is used for repeated actions. Example:

for (int i = 0; i < 5; i++) {
    printf("%d ", i);
}

15. Break and Continue

Use break to exit a loop, and continue to skip to the next iteration. Example:

for (int i = 0; i < 5; i++) {
    if (i == 3) break;
    printf("%d ", i);
}

16. Arrays

Arrays store multiple values of the same type. Example:

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

17. Strings

Strings are arrays of characters. Example:

char greeting[] = "Hello";
printf("%s", greeting);

18. User Input

Use scanf() for user input. Example:

int age;
printf("Enter your age: ");
scanf("%d", &age);
printf("You are %d years old.", age);

19. Memory Address

Use the & operator to get a variable’s address. Example:

int number = 10;
printf("%p", &number); // Prints the memory address of number

20. Pointers

Pointers store memory addresses. Example:

int number = 10;
int* ptr = &number;
printf("%d", *ptr); // Outputs 10

21. Functions

Functions organize reusable code blocks. Example:

int add(int a, int b) {
    return a + b;
}
printf("Sum: %d", add(2, 3));

22. Function Parameters

Functions can have parameters. Example:

void greet(char name[]) {
    printf("Hello, %s", name);
}
greet("Alice");

23. Scope

Variables have local or global scope. Example:

int globalVar = 10;

void test() {
    int localVar = 20; // Local to this function
}

24. Function Declaration

Declare a function before calling it if it appears later in the file. Example:

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

25. Recursion

Recursion occurs when a function calls itself. Example:

int factorial(int n) {
    if (n == 0) return 1;
    return n * factorial(n - 1);
}

26. Math Functions

Use <math.h> for math functions. Example:

#include <math.h>
double result = sqrt(25.0); // result is 5.0

27. Files

File handling allows reading and writing data. Example:

FILE *file = fopen("example.txt", "w");
fprintf(file, "Hello, World!");
fclose(file);

28. Create Files

Open a file for writing with w. Example:

FILE *file = fopen("newfile.txt", "w");
if (file) {
    fclose(file);
}

29. Write to Files

Use fprintf() to write data to a file. Example:

FILE *file = fopen("data.txt", "w");
fprintf(file, "Data here");
fclose(file);

30. Read Files

Read data from a file with fscanf(). Example:

FILE *file = fopen("data.txt", "r");
int data;
fscanf(file, "%d", &data);
fclose(file);

31. Structures

Structures group variables of different types. Example:

struct Person {
    char name[50];
    int age;
};
struct Person person1 = {"Alice", 30};
printf("%s is %d years old", person1.name, person1.age);

32. Enums

Enums define named integer constants. Example:

enum Day {MON, TUE, WED};
enum Day today = MON;

33. Memory Management

Use malloc() and free() for dynamic memory. Example:

int *ptr = malloc(10 * sizeof(int));
free(ptr);