PHP String Handling

A string is a series of characters, like “Hello PHP”. Working with text is one of the most common jobs in web development, so PHP gives many functions to handle strings.

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Create and join strings

You can write a string in single quotes or double quotes. In double quotes PHP replaces the variables with their values, in single quotes it does not. The dot (.) joins strings.

<?php
$name = "Robin";

echo "Hello $name<br>";
echo 'Hello $name<br>';
echo "Hello " . $name . "!";
?>

Output:

See the details in single vs double quote strings.

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Common string functions

Function	What it does	Example result
strlen($s)	Length in bytes. Use mb_strlen() for non-English text. See strlen vs mb_strlen	strlen(“PHP”) = 3
strtoupper(), strtolower()	Change the case	“hello” to “HELLO”
ucfirst(), ucwords()	Capital first letter of text or of each word	“hello world” to “Hello World”
trim(), ltrim(), rtrim()	Remove spaces from the ends	” hi ” to “hi”
substr($s, start, length)	Take a part of a string	substr(“Hello World”, 6, 5) = “World”
strrev($s)	Reverse a string	“Hello” to “olleH”
str_replace()	Replace text. See replace a part of a string	str_replace(“a”, “o”, “cat”) = “cot”
strpos()	Find the position of a text. See PHP strpos()	strpos(“Hello”, “l”) = 2
str_contains()	Check if text exists (PHP 8). See contains a substring	true or false
str_word_count()	Count the words. See count words	2
explode(), implode()	Split to an array and join back. See explode() and implode()

<?php
echo strtoupper("hello") . "<br>";
echo ucwords("hello world") . "<br>";
echo substr("Hello World", 6, 5) . "<br>";
echo strrev("Hello") . "<br>";
echo "[" . trim("  hi  ") . "]<br>";
var_dump(str_starts_with("Tutorials Class", "Tut"));
?>

Output:

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Format strings and numbers

<?php
echo sprintf("Price: %.2f", 99.5) . "<br>";
echo number_format(1234567.891, 2);
?>

Output:

sprintf() puts values into a text pattern, and number_format() adds thousand separators and fixes the decimals.

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Special characters and safety

• Use a backslash to write special characters in double quotes, like \n (new line) and \" (a quote).
• Before you print user text in a page, convert it with htmlspecialchars(). See XSS and strip_tags().

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Exercises & Assignments
Write a PHP program to reverse the string
Write a PHP program to find the length of the string
Write a PHP program to count the words in the string
Write a PHP program to convert a string into uppercase
PHP Array to String Conversion (favourite colours chosen by user)

Interview Questions & Answers
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