Functions · Lesson 9 of 9

Built-in PHP Functions

Use PHP standard-library functions instead of rewriting common operations.

Lesson

PHP includes functions for strings, arrays, dates, filtering, and many other tasks. Check function documentation for parameter types, return values, and edge cases rather than guessing. Prefer well-tested standard functions, and be explicit about encoding and locale when handling text or dates. This example combines filtering and joining to format a list without a manual loop. Further guidance Treat a function as a small contract: name its inputs, state what it returns, and avoid hidden dependencies. Test a representative value and an edge case. Keep a function focused; callers should decide how to display a returned result or handle a reported failure. Practice task: Create a fresh example for Built-in PHP Functions. Predict the result before running it, then change one input and explain why the result changes. Test a normal case and one boundary or invalid case where it applies. Compare your output with the example and note one rule you would use in a real project.

Code examples

PHP

$parts = ['PHP', '', 'MySQL'];
$labels = array_filter($parts, fn (string $part): bool => $part !== '');
echo implode(' + ', $labels);

Expected output

PHP + MySQL

Key points

Use PHP standard-library functions instead of rewriting common operations.
Keep inputs, return values, and side effects explicit.
Prefer focused functions that are easy to test independently.

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