PHP · Theory

Functions

Theory

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Functions is a PHP idea you prove with Dev walking through Functions, not with a slogan.

Do Functions once by hand. one Functions step Dev can write from memory. Change one input. Say the new result out loud.

Functions exists so Dev can keep Dev walking through Functions correct in a campus project.

Use Functions when Dev walking through Functions must stay clear. If a simpler PHP step works, use that instead.

Don’t do this with Functions — copy-pasting Functions without a dry-run. Interviewers spot it in ten seconds.

Place Functions next to nearby PHP work — one Functions step Dev can write from memory is the link.

Viva for Functions: what it is → one Functions step Dev can write from memory → the mistake (copy-pasting Functions without a dry-run).

Exam tip

Say Functions in one breath, then one Functions step Dev can write from memory, then copy-pasting Functions without a dry-run.

<?php
function greet(string $name, int $n = 1): string {
  return str_repeat("Hi $name! ", $n);
}
echo greet("Asha");
echo greet("Dev", 2);

Functions — typed params and return types make PHP APIs clearer.

DefFunctions — Dev uses it for Dev walking through Functions in a campus project.
RuleFunctions → one Functions step Dev can write from memory.
RememberFunctions + a .php page (a campus project).
UseFunctions in a campus project (Dev walking through Functions).
TrapFunctions — copy-pasting Functions without a dry-run.
ExFunctions → Dev walking through Functions.