PHP · Theory

Call By Reference

Theory

29/352

Call By Reference

Call By Reference is a PHP topic. In plain words you use it for function add($a, $b) in a marks helper. Don’t start with a slogan — start with that picture.

Smallest example: function name($x) { return $x; }. Type it, run it, and say what you see. If you can do that from memory, you know Call By Reference.

From the example next to this theory — Call By Reference: scores array, print avg, then high marks.

Trap — no return so the caller gets null. Fix that before you talk about advanced PHP.

Viva — what is Call By Reference? Then show function name($x) { return $x; }. Then name the trap.

Exam tip

What is Call By Reference? Show this: function name($x) { return $x; }. Trap: no return so the caller gets null.

Example

<?php
// Call By Reference
$scores = [80, 90, 70];
$avg = array_sum($scores) / count($scores);
echo "avg=" . number_format($avg, 1) . "\n";
foreach ($scores as $s) {
  if ($s >= 80) echo "high: $s\n";
}

Call By Reference: scores array, print avg, then high marks. Say the output.

Short notes

DefCall By Reference — function add($a, $b) in a marks helper.
Rulefunction name($x) { return $x; }
Trapno return so the caller gets null
Usea marks helper

PHP · Theory

Call By Reference

← All stacks

Theory

29/352

Call By Reference

Call By Reference is a PHP topic. In plain words you use it for function add($a, $b) in a marks helper. Don’t start with a slogan — start with that picture.

Smallest example: function name($x) { return $x; }. Type it, run it, and say what you see. If you can do that from memory, you know Call By Reference.

From the example next to this theory — Call By Reference: scores array, print avg, then high marks.

Trap — no return so the caller gets null. Fix that before you talk about advanced PHP.

Viva — what is Call By Reference? Then show function name($x) { return $x; }. Then name the trap.

Exam tip

What is Call By Reference? Show this: function name($x) { return $x; }. Trap: no return so the caller gets null.

Example

<?php
// Call By Reference
$scores = [80, 90, 70];
$avg = array_sum($scores) / count($scores);
echo "avg=" . number_format($avg, 1) . "\n";
foreach ($scores as $s) {
  if ($s >= 80) echo "high: $s\n";
}

Call By Reference: scores array, print avg, then high marks. Say the output.

Short notes

DefCall By Reference — function add($a, $b) in a marks helper.
Rulefunction name($x) { return $x; }
Trapno return so the caller gets null
Usea marks helper

Call By Reference

Example

Short notes

Questions

Call By Reference

Example

Short notes

Questions