如何替换字符串中的所有空格但仅在ID属性中？

Question

I have a next string:

$str = '<h2 id="name of header">Name of header</h2>';

Need to replace all spaces in ID attribute. Example:

$str = '<h2 id="name-of-header">Name of header</h2>';

IS there any way I can do that?

Answer 1

Since the id is the only portion between quotes - explode it at the quotes - use str_replace to replace the spaces in the middle portion (the id part) and then join them back up to a single string.

this will mean that ...explode('"',$str); will give you the results of:

$str_portions[0] = <h2 id=
$str_portions[1] = name of header
$str_portions[2] = >Name of header</h2>;

str_replace the spaces with hyphens in the $str_portions[1] using str_replace(' ', '-', $str_portions[1]); will give:

$str_portions[1] = name-of-header

so the following is:

$str = '<h2 id="name of header">Name of header</h2>';

$str_portions = explode('"',$str); // splits the original statement into 3 parts
$str_id = str_replace(' ', '-', $str_portions[1]);  // replaces the spaces with hyphens in the 2nd (id) portion
$str = $str_portions[0] . '"' . $str_id . '"' . $str_portions[2]; // joins all 3 parts into a single string again - reinserting the quotes
echo $str; // gives  '<h2 id="name-of-header">Name of header</h2>';

Answer 2

<?php
$str = '<h2 id="name of header">Name of header</h2>';

$new_str = preg_replace_callback('#\"([^"]*)\"#', function($m){
    return('"'. str_replace(' ', '-', $m[1]) .'"');
}, $str);
echo $new_str;
 ?>

It will work perfectly thanks

Answer 3

You could use a preg_replace to replace only the part you want to replace within your string.

You could also use str_replace but then, you have to select ONLY the part you want to replace.

With preg_replace you could do something like:

<?php
$str = '<h2 id="name of header">Name of header</h2>';;

$new_str = preg_replace(
    'id="([\w\s]+)"', 
    'id="' . str_replace(' ', '-', $1) . '"', 
    $str);
?>

Where id="([\\w\\s]+)" would select only the ID part, and str_replace(' ', '-', "$1") would replace the spaces in it with a '-'.

But if you are not familiar with regex, I suggest you use gavgrif solution that is simpler.