C language from 0

Embark on your C programming journey! While initially daunting, mastering C's fundamentals is achievable with the right approach. This guide provides a structured introduction, progressing from basic concepts to more advanced topics.

Table of Contents

1. C Basics and Data Types
2. User Input and Output
3. Conditional Statements (including shortcuts)
4. Switch Statements
5. Arrays: One and Two-Dimensional
6. Nested Loops
7. Functions: Structure and Usage
8. Structures (structs)
9. Pointers

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C Basics and Data Types

C programs adhere to a standard structure and utilize various data types for variables. A simple example:

#include <stdio.h>

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

Key Concepts:

• Data Types:
  • int: Integers (e.g., int x = 10;)
  • float and double: Floating-point numbers (decimals) (e.g., float pi = 3.14;)
  • char: Single characters or ASCII codes (e.g., char letter = 'A';)
  • bool: Boolean values (true/false) (requires <stdbool.h></stdbool.h>)

// Data Type Examples:
int a = 40;         // Integer (4 bytes)
short int b = 32767; // Short Integer (2 bytes)
unsigned int c = 4294967295; // Unsigned Integer (4 bytes)
float d = 9.81;     // Float (4 bytes)
double e = 3.14159; // Double (8 bytes)
bool f = true;      // Boolean (1 byte)
char g = 'e';       // Character (1 byte)
char h = 100;      // Character (1 byte)
char name[] = "Example"; // String (array of characters)

// Variable declaration and initialization
int age;      // Declaration
age = 5;      // Initialization
char letter = 'C'; // Declaration and initialization

// Displaying variables
printf("You are %d years old\n", age); // Integer
printf("Hello %s\n", name);           // String
printf("Learning %c\n", letter);      // Character

// Format specifiers: %d (int), %s (string), %c (char), %f (float), %.2f (float to 2 decimal places)

• Operators: , -, *, /, % (modulo), (increment), -- (decrement). Remember type casting for accurate results (e.g., float z = 5 / (float)2;).

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User Input and Output

For user input in VS Code, use the Terminal tab.

int age;
char name[25];

// Integer Input
printf("Enter your age: ");
scanf("%d", &age);
printf("You are %d years old\n", age);

// String Input (using `fgets` for safer input)
printf("Enter your name: ");
fgets(name, sizeof(name), stdin); // fgets handles spaces
name[strcspn(name, "\n")] = 0; // Remove trailing newline from fgets
printf("Hello, %s!\n", name);

Case sensitivity matters in C. Use functions like toupper() from <ctype.h></ctype.h> for case-insensitive comparisons.

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Conditional Shortcuts (Ternary Operator)

The ternary operator provides a concise way to write if-else statements:

int max = (a > b) ? a : b; // Equivalent to an if-else statement

---

Switch Statements

Handle multiple conditions efficiently:

char grade = 'A';

switch (grade) {
    case 'A':
        printf("Excellent!\n");
        break;
    case 'B':
        printf("Good!\n");
        break;
    default:
        printf("Try again!\n");
}

Always include a default case.

---

Arrays

Arrays store collections of same-type variables:

int numbers[5] = {10, 20, 30, 40, 50};
printf("%d\n", numbers[0]); // Accesses the first element (10)

// 2D Array
int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};

// Array of Strings
char cars[][10] = {"BMW", "Tesla", "Toyota"};

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Nested Loops

Loops within loops, useful for processing multi-dimensional data: (Example omitted for brevity, but easily constructed using nested for loops).

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Functions

Functions promote code reusability:

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

int main() {
    greet("Alice");
    return 0;
}

---

Structures (structs)

Group related variables:

struct Player {
    char name[50];
    int score;
};

struct Player player1 = {"Bob", 150};
printf("Name: %s, Score: %d\n", player1.name, player1.score);

---

Pointers

Variables storing memory addresses:

#include <stdio.h>

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

Pointers are crucial for dynamic memory allocation. This guide provides a solid foundation. Consistent practice is key to mastering C programming.

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