PHP - Function ctype_alnum()

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The PHP Character type checking ctype_alnum() function is used to check whether characters in the given text are alphanumeric. An "alphanumeric" character refers to a letter or digit. For example, a string "abC19y" contains an alphanumeric character.

This function returns a boolean value true if every character in the text is a letter or digit; otherwise, it returns false. If the provided text is empty(), it always returns false.

Syntax

Following is the syntax of the PHP Character type Checking ctype_alnum() function −

ctype_alnum (mixed $text): bool

Parameters

This function accepts the following parameters −

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

Return Value

This function returns 'true', if every character in the text is either a letter or a digit, 'false' otherwise.

Example 1

If the given text is "alphanumeric" text, the PHP ctype_alnum() function will return true −

<?php
   $text = "Hello21";
   echo "The given text: ".$text;
   #using alnum() function
   echo "\nIs the text is alphanumeric? ";
   var_dump(ctype_alnum($text));
?>

Output

The above program will produce the following results −

The given text: Hello21
Is the text is alphanumeric? bool(true)

Example 2

If the given string is not an alphanumeric string, the PHP ctype_alnum() function returns false −

<?php
   $text = "@Hello#^";
   echo "The given text: ".$text;
   #using alnum() function
   echo "\nIs the text is alphanumeric? ";
   var_dump(ctype_alnum($text));
?>

Output

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

The given text: @Hello#^
Is the text is alphanumeric? bool(false)

Example 3

Checking multiple strings (texts).

In the following example, we declare an array containing multiple texts and will check each string to determine whether they are alphanumeric using the ctype_alnum() function −

<?php
   $texts = array('Tutorialspoint', 'tutorix!@13#');
   echo "The given Strings are: ";
   foreach($texts as $text){
	   echo $text." ";
   }
   foreach($texts as $text){
	   if(ctype_alnum($text)){
		   echo "\nThe string '$text' is an alphanumeric.";
	   }
	   else{
		   echo "\nThe string '$text' is not an alphanumeric.";
	   }
   }
?>

Output

This will produce the following output −

The given Strings are: Tutorialspoint tutorix!@13#
The string 'Tutorialspoint' is an alphanumeric.
The string 'tutorix!@13#' is not an alphanumeric.

Example 4

If the provided text or string is empty "", this function will always return 'false' −

<?php
   $text = "";
   echo "The given Strings are: ".$text;
   echo "\nIs the '$text' is an alphanumeric? ";
   var_dump(ctype_alnum($text));
?>

Output

Once the above program is executed, it will return 'false' −

The given Strings are:
Is the '' is an alphanumeric? bool(false)