How to Use PHP trim() to Remove Whitespace and Specified Characters

In PHP development, handling strings is common, and the trim() function is a frequently used tool for removing whitespace from both ends of a string.

The basic usage of trim() is:

string trim(string $str, string $character_mask = " \t\n\r\0\x0B")

The function accepts two parameters: the target string $str and an optional character mask $character_mask . By default, the mask removes spaces, tabs, newlines, and other common whitespace characters.

Example 1 shows the default behavior:

$str = "  Hello, World!   ";
echo "Original string: '" . $str . "'";
echo "Trimmed string: '" . trim($str) . "'";

Output:

Original string: '  Hello, World!   '
Trimmed string: 'Hello, World!'

In this example, the extra spaces around $str are removed by trim($str) , leaving a clean string.

Beyond the default usage, trim() can also remove specific characters by providing a $character_mask . Example 2 demonstrates removing the characters "X" and "O" from both ends of a string:

$str = "XOXHello, World!OXOX";
echo "Original string: '" . $str . "'";
echo "Trimmed string: '" . trim($str, "XO") . "'";

Output:

Original string: 'XOXHello, World!OXOX'
Trimmed string: 'Hello, World!'

This shows that trim($str, "XO") successfully strips the leading and trailing "X" and "O" characters.

Note that trim() only removes characters from the start and end of the string; characters inside the string remain untouched.

Summary

Through this guide, you have learned the basic usage of the trim() function, which can easily remove whitespace or specified characters from the ends of a string, making string handling in PHP more efficient.