Functions

Simple C function

#include <stdio.h>

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

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

Function that returns a value

#include <stdio.h>

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

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

C function with string parameter

#include <stdio.h>

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

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

C function that returns a value

#include <stdio.h>

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

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

C function with multiple parameters

#include <stdio.h>

int max(int a, int b, int c) {
    int maximum = a;
    if (b > maximum) maximum = b;
    if (c > maximum) maximum = c;
    return maximum;
}

int main() {
    int result = max(10, 25, 15);
    printf("Maximum is: %d\n", result);
    return 0;
}

C recursive function example

#include <stdio.h>

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

int main() {
    int n = 5;
    printf("Factorial of %d is: %d\n", n, factorial(n));
    return 0;
}

C function with array parameter

#include <stdio.h>

void printArray(int arr[], int size) {
    for (int i = 0; i < size; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

int main() {
    int arr[] = {1, 2, 3, 4, 5};
    int size = sizeof(arr) / sizeof(arr[0]);
    printArray(arr, size);
    return 0;
}

C function with function pointers

#include <stdio.h>

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

int multiply(int a, int b) {
    return a * b;
}

int main() {
    int (*operation)(int, int);
    
    operation = add;
    printf("Addition: %d\n", operation(5, 3));
    
    operation = multiply;
    printf("Multiplication: %d\n", operation(5, 3));
    
    return 0;
}

C function with variable number of arguments

#include <stdio.h>
#include <stdarg.h>

int sum(int count, ...) {
    va_list args;
    va_start(args, count);
    
    int total = 0;
    for (int i = 0; i < count; i++) {
        total += va_arg(args, int);
    }
    
    va_end(args);
    return total;
}

int main() {
    printf("Sum: %d\n", sum(3, 10, 20, 30));
    printf("Sum: %d\n", sum(5, 1, 2, 3, 4, 5));
    return 0;
}