Calling functions

Learn to call a function by its name with parentheses.

Calling functions

To run a function, write its name followed by parentheses: greet();. This is called a call. When called, the function body runs from top to bottom.

You can call the same function as many times as you like. Writing greet(); greet(); runs the body twice. The call may sit below or above the definition; PHP registers functions while loading the file.

Call and definition order

PHP registers top-level function definitions while loading the file. So a call may be written before the definition. For readability, though, it is common to keep definitions above and calls below.

Once a function is defined, you can call it from anywhere in the same file as many times as you wish; you decide the number of calls. Multiple functions may sit side by side as well.

Exercise Call the same function twice

Define a parameterless function named announceStart. In the body, write echo "Starting!" . "\n";. Then call the function twice.

Show example solution

Define it, then write announceStart(); twice.
Example solution:
<?php
// Define announceStart and call it twice
function announceStart() {
    echo "Starting!" . "\n";
}
announceStart();
announceStart();

Test yourself

Complete the function call

function startEngine() {
    echo "Vroom";
}

____;

Show answer

function startEngine() {
    echo "Vroom";
}

startEngine();

What is the output of the code below?
```
function ding() {
    echo "X";
}

ding();
ding();
ding();
```
- X X X
- X
- XXX
- X, X, X
Show answer

XXX — Correct. Three calls produce three X's side by side; echo adds no space.
Match calling terms

greet

Function name
greet()

Call expression
function greet() { ... }

Definition

Next lesson: Returning values

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