C Summary - Functions

main.c

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Expected output

Lesson notes

Summary - Functions

Combine prototypes, parameters and recursion to write a factorial calculator.

Summary: Functions

In this group you saw how to define functions, call them, return values, take parameters and use recursion.

void f(void) { ... }: a function that returns no value
int f(int x): takes a parameter, returns a value
return: sends the value back to the caller
Prototype: a signature declaration before the definition
Recursion: the function calls itself; a base case is required

Now let's combine these in one task.

Exercise Call a function twice

Define void stars(void) with body printf("***\n");. Call it twice from main. Output should be two lines of ***.

Show example solution

#include <stdio.h>

void stars(void) {
    printf("***\n");
}

int main(void) {
    stars();
    stars();
    return 0;
}

Test yourself

What should the return type be if a function returns no value?
- char
- int
- void
- double
Show answer

void — void means the function returns no value.

Call expression

int result = add(3, ____);  /* add(3, 5) call */

Show answer

int result = add(3, 5);  /* add(3, 5) call */

Match function concepts

return

returns value
void

no return value
prototype

signature declaration
recursion

calls itself

Next lesson: What is a pointer?