A cheat sheet is a handy reference tool that provides quick access to the most commonly used features and syntax of a programming language. In this article, we will present a comprehensive C language cheat sheet with examples. Whether you’re a beginner or an experienced programmer, this cheat sheet will serve as a valuable resource for writing C programs efficiently.
Basic Syntax and Data Types
C is a procedural programming language known for its low-level control over hardware.
Hello World Program:
#include <stdio.h>
int main() {
printf("Hello, World!\n");
return 0;
}
Variable Declaration and Initialization:
int age = 25;
float salary = 2500.50;
char grade = 'A';
Control Flow Statements
Control flow statements manage the program’s execution based on conditions and loops.
if-else Statement:
if (x > 10) {
printf("x is greater than 10\n");
} else {
printf("x is less than or equal to 10\n");
}
for Loop:
for (int i = 0; i < 5; i++) {
printf("Iteration: %d\n", i);
}
Functions and Pointers
Functions are blocks of reusable code that perform specific tasks. Pointers hold memory addresses.
Function Declaration and Definition:
int add(int a, int b) {
return a + b;
}
Pointer Declaration and Usage:
int num = 10;
int *ptr = #
Pointers and Memory Allocation:
int* ptr = NULL;
ptr = (int*)malloc(sizeof(int));
*ptr = 10;
Arrays and Strings
Arrays store multiple elements of the same data type. And string a type of character array.
Array Declaration and Initialization:
int numbers[5] = {1, 2, 3, 4, 5};
String Manipulation:
char name[] = "John";
printf("Length of name: %d\n", strlen(name));
Input and Output
Input and output operations enable interaction with users and data exchange.
Reading Input:
int number;
printf("Enter a number: ");
scanf("%d", &number);
Writing Output:
printf("The result is: %d\n", result);File Handling
File Opening and Reading:
FILE* file = fopen("data.txt", "r");
if (file != NULL) {
char buffer[100];
fgets(buffer, 100, file);
printf("Data: %s\n", buffer);
fclose(file);
}
Memory Management
Memory management involves allocating and deallocating memory.
Dynamic Memory Allocation and Deallocation:
int* numbers = (int*)malloc(5 * sizeof(int));
numbers[0] = 1;
free(numbers);
Error Handling
Checking for Null Pointers:
int* ptr = NULL;
if (ptr == NULL) {
printf("Pointer is NULL\n");
}
Additional Libraries
Libraries are collections of precompiled code that provide additional functionality.
Including Math Library:
#include <math.h>
double result = sqrt(25);
Preprocessor Directives
Preprocessor directives modify the source code before compilation.
Include Header File:
#include <stdio.h>
Conclusion
This C language cheat sheet provides a quick reference guide for fundamental concepts, syntax, and examples. Use it as a valuable tool to write efficient C programs. However, it’s always recommended to consult official documentation for a more detailed understanding.