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

The trim() function is a widely used PHP built‑in that removes whitespace or other specified characters from the beginning and end of a string.

1. Function Syntax

The syntax of trim() is:

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

The first argument is the target string, and the optional second argument defines a mask of characters to strip; by default it removes spaces, tabs, newlines, carriage returns, null bytes, and vertical tabs.

2. Removing Leading and Trailing Spaces

To strip only whitespace, pass the string to trim():

$str = "  hello world  ";
$result = trim($str);
echo $result; // outputs: hello world

3. Removing Specified Characters

You can also specify characters to remove via the second parameter $character_mask:

$str = "Hello, World!";
$result = trim($str, "H!");
echo $result; // outputs: ello, World

4. Common Examples

Removing whitespace and newline characters:

$str = "  Hello, World!  
";
$result = trim($str);
echo $result; // outputs: Hello, World!

Removing whitespace, newline, and tab characters:

$str = "    Hello, World!
";
$result = trim($str, "
    ");
echo $result; // outputs: Hello, World!

5. Summary

The trim() function is essential for cleaning user input and ensuring data accuracy in PHP applications, offering flexible removal of both default whitespace and any custom characters you define.