How to case strings in PHP

In PHP, you can use: strtoupper() function, strtolower() function, ucfirst() function, lcfirst() function to case strings. The following article will give you a detailed introduction, I hope it will be helpful to you.

strtoupper() function

strtoupper() function can take a string as a parameter, and then The string is converted to all uppercase and returned.

Basic syntax:

strtoupper(string)

Example:

<?php 
function toUpper($string){ 
    return(strtoupper($string)); 
} 
$string="Hello world!";   
echo (toUpper($string)); 
?>

Output:

##strtolower( )Function

strtolower() function can take a string as a parameter, then convert all strings to lowercase and return.

Basic syntax:

strtolower(string)

Example:

<?php 
function toUpper($string){ 
    return(strtolower($string)); 
} 
$string="JAVASCRIPT";   
echo (toUpper($string)); 
?>

Output:

##ucfirst( )Function ucfirst() function can take a string as a parameter, and then convert the first letter of the string to uppercase, leaving other characters unchanged, and return.

Basic syntax:

ucfirst(string)

Example:

<?php 
function toUpper($string){ 
    return(ucfirst($string)); 
} 
$string="hello world!";   
echo (toUpper($string)); 
?>

Output:

##lcfirst( ) Function

lcfirst() function can take a string as a parameter, and then convert the first letter of the string to lowercase, leaving the other characters unchanged, and return it.

Basic syntax:

lcfirst(string)

Example:

<?php 
function toUpper($string){ 
    return(lcfirst($string)); 
} 
$string="PHP中文网！";   
echo (toUpper($string)); 
?>

Output:

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