Chapter 8

Can we make some custom statement ?

Yes, of course, proc can do it.

proc call() {
    std::print("hello");
    std::print("we can make some procedure");
}

// call it
call();

We can use parameter, when we call it, we can use using some values.

proc call_name(name) {
    std::print("wello " + name);
}

// or we can make specification with data types
proc add_multiple(first: int, second: int) {
    std::print(first + second * first);
}

call_name("jane");
add_multiple(5, 3);

Void Functions

Functions that don't return a value should declare : void:

proc greet(): void {
    std::print("Hello, World!");
}

proc print_header(title: string): void {
    std::print("====================================");
    std::print("  " + title);
    std::print("====================================");
}

greet();
print_header("Welcome");

Why use : void?

• Explicit intent: Makes it clear the function doesn't return a value
• Type safety: Prevents accidentally returning a value from a procedure
• Best practice: Recommended for all functions that don't return values

Return Values

You can return values from functions by declaring the return type:

proc answer(value: int): int {
    return value + 30;
}

var number: int = answer(20);
std::print(number);

Or use an explicit return type for clarity:

proc answer(value: int): int {
    return value + 12;
}

var number: int = answer(3) + 20;
std::print(number);

Implicit Return

The last expression in a function is automatically returned:

proc add(a: int, b: int): int {
    a + b  // implicitly returned
}

var sum = add(10, 20);
std::print(sum);  // prints 30

Lets we play it

How about fibonacci ?

proc fibonacci(number: int): int {
  if (number < 2) {
    return number;
  }

  return fibonacci(number - 1) + fibonacci(number - 2);
}

for (var i = 0; i < 20; i++) {
  var answer = fibonacci(i);
  std::print(answer);
}

Function Best Practices

1. Use void for procedures - Functions that only perform side effects (like printing) should return : void
2. Name descriptively - print_header() not ph()
3. Keep functions focused - Each function should do one thing well
4. Use explicit return types - Makes code easier to understand