08. Functions

Why functions, parameters, return, live modular code

Goals:

Function se code reuse
Parameters aur return
Call by value (intro)

1. Function kya hai?

Function = named block jo kaam karke (optional) value wapas karta hai.

Fayda: ek baar likho, kai jagah call karo; program readable banta hai.

Live practice 1 — add function

Function body me formula badal ke dekho.

#include <cstdio>

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

int main() {
    printf("2+5 = %d\n", add(2, 5));
    printf("10+20 = %d\n", add(10, 20));
    return 0;
}

Live practice 2 — Is even?

Return 1/0 se even check.

#include <cstdio>

int is_even(int n) {
    if (n % 2 == 0) return 1;
    return 0;
}

int main() {
    printf("4 even? %d\n", is_even(4));
    printf("7 even? %d\n", is_even(7));
    return 0;
}

C me default call by value: function ko copy milti hai. Original variable change karne ke liye pointers (aage).

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