C Programming Language Cheatsheet

Whether you are a seasoned developer or just starting your programming journey, having a handy cheatsheet for the C programming language can be a lifesaver. C is a powerful and versatile programming language that forms the foundation for many other languages. In this cheatsheet, we’ll cover the essential elements of C, from basic syntax to advanced concepts.

1. Basic Syntax

1.1 Hello, World!

#include <stdio.h>

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

1.2 Variables and Data Types

int age = 25;               // Integer
float salary = 50000.50;    // Floating-point
char grade = 'A';           // Character

1.3 Constants

#define PI 3.14159
const int MAX_SIZE = 100;

1.4 Operators

int a = 5, b = 3;
int sum = a + b;
int difference = a - b;
int product = a * b;
float quotient = (float)a / b;  // Type casting for accurate division

2. Control Flow

2.1 Conditional Statements

if (condition) {
    // Code to execute if the condition is true
} else if (another_condition) {
    // Code to execute if another_condition is true
} else {
    // Code to execute if no conditions are true
}

2.2 Loops

2.2.1 While Loop

while (condition) {
    // Code to repeat while the condition is true
}

2.2.2 For Loop

for (int i = 0; i < 5; i++) {
    // Code to repeat five times
}

2.2.3 Do-While Loop

do {
    // Code to execute at least once
} while (condition);

3. Functions

3.1 Function Declaration and Definition

// Function Declaration
int add(int x, int y);

// Function Definition
int add(int x, int y) {
    return x + y;
}

3.2 Recursion

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

4. Arrays and Strings

4.1 Arrays

int numbers[5] = {1, 2, 3, 4, 5};

4.2 Strings

char greeting[] = "Hello, C!";

5. Pointers

int num = 10;
int *ptr = #   // Pointer declaration and initialization

6. Structures

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

7. File Handling

7.1 File Opening and Closing

FILE *file = fopen("example.txt", "r");
if (file != NULL) {
    // Code to read or write to the file
    fclose(file);
}

8. Memory Allocation

8.1 Dynamic Memory Allocation

int *arr = (int *)malloc(5 * sizeof(int));

9. Advanced Concepts

9.1 Multithreading

#include <pthread.h>

void *thread_function(void *arg) {
    // Code to be executed in the thread
}

int main() {
    pthread_t thread;
    pthread_create(&thread, NULL, thread_function, NULL);
    pthread_join(thread, NULL);
    return 0;
}

9.2 Preprocessor Directives

#define DEBUG 1

#if DEBUG
    // Code included only if DEBUG is defined
#endif

This cheatsheet covers the fundamental aspects of the C programming language, providing a quick reference for both beginners and experienced developers. Keep this handy guide by your side, and you’ll be well-equipped to tackle any C programming challenge that comes your way. Happy coding!

Refer to the official documentation for more in-depth information and examples.