PHP make sure string has no whitespace?

To check whether a string contains whitespace in PHP, you can use the preg_match() function with a regular expression pattern. This method detects any whitespace characters including spaces, tabs, and newlines.

Syntax

preg_match('/\s/', $yourVariableName);

Example − Checking for Whitespace

The following example demonstrates how to check if a string contains whitespace ?

<?php
$name = "John Smith";
if (preg_match('/\s/', $name)) {
    echo "The name ($name) has whitespace";
} else {
    echo "The name ($name) has no whitespace";
}
?>

The name (John Smith) has whitespace

Example − String Without Whitespace

Here's an example with a string that contains no whitespace ?

<?php
$username = "JohnSmith";
if (preg_match('/\s/', $username)) {
    echo "The username ($username) has whitespace";
} else {
    echo "The username ($username) has no whitespace";
}
?>

The username (JohnSmith) has no whitespace

Alternative Methods

You can also use other approaches to check for whitespace ?

<?php
$text = "Hello World";

// Method 1: Using ctype_space() for strings with only whitespace
if (ctype_space($text)) {
    echo "String contains only whitespace";
}

// Method 2: Comparing with trimmed version
if ($text !== trim($text)) {
    echo "String has leading or trailing whitespace";
}

// Method 3: Using strpos() to find space
if (strpos($text, ' ') !== false) {
    echo "String contains spaces";
}
?>

String has leading or trailing whitespace
String contains spaces

Conclusion

The preg_match('/\s/', $string) function is the most reliable method to detect any whitespace in a string. It returns 1 if whitespace is found, 0 if not found.