Strings and Text Processing

What you will learn

Use concatenation, interpolation, and common string functions.
Split and join text with explode() and implode().
Search and replace text deliberately.
Explain why HTML escaping is separate from input validation.

The code from this chapter

Type these programs yourself. The predictions below are the exercises; the explanations are in the book.

7.1 Strings as Data

Type this into a file, predict the output, then run it.

PHP

<?php

declare(strict_types=1);

$word = "café";

echo strlen($word) . PHP_EOL;
echo mb_strlen($word) . PHP_EOL;
echo "[" . trim("   spaced   ") . "]" . PHP_EOL;

7.2 Split, Join, Search, Replace

Type this into a file, predict the output, then run it.

PHP

<?php

declare(strict_types=1);

$line = "Order 118: two notebooks";

var_dump(str_contains($line, "notebook"));
var_dump(str_contains($line, "Notebook"));
echo str_replace("two", "three", $line) . PHP_EOL;

7.3 Validation and HTML Escaping

Type this into a file, predict the output, then run it.

PHP

<?php

declare(strict_types=1);

$comment = '<b>Nice & tidy</b>';

if (trim($comment) === "") {
    echo "Comment is required." . PHP_EOL;
}

echo htmlspecialchars($comment, ENT_QUOTES, "UTF-8") . PHP_EOL;

TPRM Lab 7.1: Split and Join Words

Type this into a file, predict the output, then run it.

PHP

<?php

declare(strict_types=1);

$text = "red,green,blue";
$colors = explode(",", $text);

echo $colors[0] . PHP_EOL;
echo count($colors) . PHP_EOL;
echo implode(" | ", $colors) . PHP_EOL;

TPRM Lab 7.2: Escape Text for HTML

Type this into a file, predict the output, then run it.

PHP

<?php

declare(strict_types=1);

$name = '<strong>Maya & Co.</strong>';

$safe = htmlspecialchars($name, ENT_QUOTES, "UTF-8");

echo $safe . PHP_EOL;