Functions – Declaration & Definition

Functions encapsulate reusable code. A prototype (declaration) tells the compiler about the function’s name, return type, and parameters before it is used.

/* Prototype */
int add(int a, int b);

int main(void) {
    int sum = add(3, 4);
    printf("%d\n", sum);
    return 0;
}

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