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substr_replace
Description
substr_replace() is used to replace part of a string with another. The substring to be replaced is specified as a range using the start and length arguments. The string to replace this range of characters is specified with the replacement argument.
Behavior of the start and length arguments is interesting, allowing for a great deal of flexibility in choosing what part of the string to replace. See the following table for details.
| Argument | Value | Behavior |
|---|---|---|
| start | Non-negative integer | Start the substring at start characters into the string. |
| start | Negative integer | Start the substring at start characters from the end of the string. |
| length | Not set | The substring extends from start to the end of the string. |
| length | Non-negative integer | End the substring length characters from the position specified by start . |
| length | Negative integer | End the substring length characters from the end of the string. |
Caution
substr_replace() only operates in a left-to-right fashion. If start is a negative value and length is less than or equal to start , length is considered as having a value of0 instead. For example:
<?php
echo substr_replace('Oops!', 'X', -2, -4);
?>
Output:OopXs!
Example
Example 1240. Demonstrate the behavior of substr_replace()
<?php
$string = '0123456789ABCDEF';
$replace = 'X';
// replace the first character
echo substr_replace($string, $replace, 0, 1), "\n",
// replace the last character
substr_replace($string, $replace, -1, 1), "\n",
// insert a character in front of the last character
substr_replace($string, $replace, -1, -3), "\n",
// insert a character at the start of a string
substr_replace($string, $replace, 0, 0), "\n";
?>
Output:
X123456789ABCDEF
0123456789ABCDEX
0123456789ABCDEXF
X0123456789ABCDEF
Example 1241. Replace the end of a long line with an ellipsis
<?php
$paragraph = <<<_Act_III_Scene_i_
Good Master Mustardseed, I know your patience well:
That same cowardly giant-like ox-beef hath devoured many a
gentleman of your house: I promise you your kindred hath made my
eyes water ere now. I desire you of more acquaintance, good
Master Mustardseed.
_Act_III_Scene_i_;
foreach(explode("\n", $paragraph) as $line) {
if (strlen($line) > 60)
$line = substr_replace($line, "...", 57);
echo $line,"\n";
}
?>
Output: Good Master Mustardseed, I know your patience well:
That same cowardly giant-like ox-beef hath devoured many a
gentleman of your house: I promise you your kindred hath...
eyes water ere now. I desire you of more acquaintance, good
Master Mustardseed.