PHP - Function ctype_lower()

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The PHP Character type checkingctype_lower()checks whether the given string (text) contains only the lowercase letter. It will also check for white space. If the string contains any white space, even if all the letters are lowercase, it will be considered non-lowercase characters.

This function returns a boolean value true if the given string consists of only the lowercase letters; otherwise, it returns false. If the given string is empty (""), this function always returns false.

Syntax

Following is the syntax of the PHP Character type checking ctype_lower() function −

ctype_lower (mixed $text): bool

Parameters

This function accepts a single parameter, which is described below −

• text (required) − A string needs to be tested.

Return Value

This function returns "true" if every character in the text is a lowercase letter, and "false" otherwise.

Example 1

If every character in the provided string (or text) is a lowercase letter, the PHP ctype_lower() function returnstrue−

<?php
   $string = "helloworld";
   echo "The given string is: $string";
   echo "\nDoes string '$string' consists only lowercase letters? ";
   #using ctype_lower() function
   var_dump(ctype_lower($string));
?>

Output

The above program produces the following output −

The given string is: helloworld
Does string 'helloworld' consists only lowercase letters? bool(true)

Example 2

If every character in the provided string (or text) is not a lowercase letter, the PHP ctype_lower() function returns false −

<?php
   $string = "TutorialsPoint";
   echo "The given string is: $string";
   echo "\nDoes string '$string' consists only lowercase letters? ";
   #using ctype_lower() function
   var_dump(ctype_lower($string));
?>

Output

After executing the above program, the following output will be displayed −

The given string is: TutorialsPoint
Does string 'TutorialsPoint' consists only lowercase letters? bool(false)

Example 3

Checking multiple strings (texts).

In the example below, we create an array of a string containing multiple strings and, using the PHP ctype_lower() function to determine whether every character in strings is in lowercase −

<?php
   $strings = array('Tutorialspoint', 'tutorix', "hello World");
   echo "The given strings are: ";
   foreach($strings as $text){
	   echo $text." ";
   }
   foreach ($strings as $test) {
      if (ctype_lower($test)) {
         echo "\nThe string '$test' consists of all lowercase letters.";
      }else {
         echo "\nThe string '$test' does not have all lowercase letters.";
      }
   }
?>

Output

Once the above program is executed, it will display the following output −

The given strings are: Tutorialspoint tutorix hello World
The string 'Tutorialspoint' does not have all lowercase letters.
The string 'tutorix' consists of all lowercase letters.
The string 'hello World' does not have all lowercase letters.

Example 4

If the provided string is empty (""), this function always returns false −

<?php
   $string = " ";
   echo "The given string is: $string";
   echo "\nDoes string '$string' consist only of lowercase letters? ";
   #using ctype_lower() function
   var_dump(ctype_lower($string));
?>

Output

Following is the output of the above program −

The given string is:
Does string ' ' consist only of lowercase letters? bool(false)