How to convert all strings to lowercase or uppercase in PHP

In php, you can use the two functions strtolower and strtoupper to convert all English characters in the string to lowercase or uppercase.

Function introduction:

strtolower() The function converts a string to lowercase.

strtoupper() Function converts a string to uppercase.

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The example is as follows:

<?php
$string = "Learn PHP string functions at jb51.net";
$lower = strtolower($string);
$upper = strtoupper($string);
print("$lower\n");
print("$upper\n");
print("\n");
?>

The output result is as follows:

learn php string functions at jb51.net
LEARN PHP STRING FUNCTIONS AT JB51.NET

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