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PHP

Replace Newlines with BR Tag and Trim Whitespaces

How to remove leading and trailing whitespace from a string and how to replace line breaks in a string with <br> tags.

  1. nl2br() function
  2. Convert newlines (or linebreaks) \r\n with <br> tags
  3. Trimming whitespaces

nl2br() function

<?php
 //Syntax
 nl2br(string $inputString, bool $use_xhtml = true): string
  • $inputString: The input string.
  • $use_xhtml: The default setting is true. nl2br( ) inserts the XHTML compliant <br /> tag when this argument is true, set false to insert <br> tag.

The nl2br( ) function generates a string by inserting the HTML break tag  <br /> before all occurrences of the newline character in the input string. See example:

<?php
 $s = 'First line
Second line
Third line';

echo nl2br($s);
/*Prints:
First line<br />
Second line<br />
Third line
*/

echo nl2br($s, false);
/*Prints:
First line<br>
Second line<br>
Third line
*/

Replace newlines \r\n with <br> tag

The nl2br() function does not replace newlines (or linebreaks) with <br> (or <br />) tags, it just inserts a <br> tag before every newline. You can use str_replace() function if you need to replace (or remove) the newlines, see the following example:

<?php
 $lines = "line 1
line 2
line3";

$output = str_replace("\r\n", '<br>', $lines);
//line 1<br>line 2<br>line3

Note: Different operating systems use different escape sequences to represent a newline (or linebreak), for example:

  • Windows uses the \r\n escape sequence
  • Unix-based OSs use \n
  • Mac OS uses \r

To cover all operating systems, you must replace all escape sequences, see the following example:

<?php
 $lines = "line 1\rline 2\nline3\r\n";
 $nl = ["\r\n","\n","\r"];
 echo str_replace($nl, '<br>', $lines);
 //line 1<br>line 2<br>line3<br>

Trimming whitespaces

PHP provides three functions that trim leading or trailing whitespace characters from strings:

<?php
 //Syntax
 trim(string $string, string $characters = " \n\r\t\v\0"): string
 rtrim(string $string, string $characters = " \n\r\t\v\0"): string
 ltrim(string $string, string $characters = " \n\r\t\v\0"): string
  1. The trim( ) function removes both leading and trailing whitespace characters.
  2. The ltrim( ) function removes leading whitespace characters.
  3. The rtrim( ) function removes trailing whitespace characters.
    The chop ( ) function is the alias of rtrim().

The following list shows whitespace characters and how they are represented in PHP:

  • “ ” Space
  • \0 null
  • \t tab
  • \v vertical tab
  • \n newline
  • \r carriage return

The trim() function helps you clean up a string by removing excess whitespace from the beginning and end of the string. The following example shows the effect of this function:

<?php
 $v = "\n   trim example.  \t";
 echo trim($v);
 //Prints: "trim example."

The ltrim() and rtrim() functions work similar to trim() function, except ltrim() only trims the left side of a string and the rtrim() function trims the right side of the string. The following example shows the effect of each:

<?php
 $v = "\n   trim example.  \t";

 echo ltrim($v);
 //Prints: "trim example.  \t"
 
 echo rtrim($v); //or chop($v);
 //Prints: "\n   trim example."

If you want to remove characters other than whitespace, you can list all characters in the second optional $characters argument.

Example: Remove trailing slash from a string

<?php
 $s = 'https://brainbell.com/';
 echo rtrim($s, '/');
 //https://brainbell.com

Example: Remove spaces, commas, and dots

<?php
 $a = ' . . Hello World, , . .,  ';
 echo trim ($a, ' ,.');
 //Hello World

 echo ltrim ($a, ' ,.');
 //Hello World, , . .,  

 echo rtrim ($a, ' ,.');
 // . . Hello World

Working with Strings: