function.php

<?php

function evenOrOdd($n){ /**parameter */
    if($n%2==0){
        return true;
    }
    return false;
}

function factorial($n){
    $result = 1;
    for($i=$n; $i>1; $i--){
        $result*=$i;
    }
    return $result;
}

function doTaskA(){
    echo "Step A Done\n";
}
function doTaskB(){
    echo "Step B Done\n";
}
function doTaskC(){
    echo "Step C Done\n";
}
function doTaskD(){
    echo "Step D Done\n";
}

function doTheLargeTask(){
    doTaskA();
    doTaskB();
    doTaskC();
    doTaskD();
}
// doTheLargeTask();

/**
 * Recursive function e nejei nijeke call kore
 * puro process hocce Recursion
 */
function src($n){
    if($n>=10){
        return;
    }
    echo $n. PHP_EOL;
    $n++;
    src($n); //Recursive
}
// src(1);

function printNumber($counter, $end, $stepping=1){
    if($counter>$end){
        return;
    }
    echo $counter."\n";
    $counter += $stepping;
    printNumber($counter, $end, $stepping);
}
// printNumber(21, 33, 3);

function fibonacci($old, $new, $end){
    static $start;
    $start = $start  ?? 1;   //$start er kicu assign na thakle 1 hobe ar thakle static e ja aca tai hobe

    if($start>$end){ return; }

    $start++;
    echo $old." ";
    $_tmp = $old + $new;
    $old = $new;
    $new = $_tmp;

    fibonacci($old, $new, $end);
}
// fibonacci(1, 3, 10);

$name = "Earth";
function doSomeThing(){
    global $name;
    echo $name;
}
// doSomeThing();

function valueData(){
    static $i;  //static scope
    $i = $i ?? 0;
    $i++;
    echo $i.PHP_EOL;
}
valueData();
valueData();
valueData();