php man page for ctype_digit

CTYPE_DIGIT(3)								 1							    CTYPE_DIGIT(3)

ctype_digit - Check for numeric character(s)

SYNOPSIS
       bool ctype_digit (string  $text)

DESCRIPTION
	Checks if all of the characters in the provided string, $text, are numerical.

PARAMETERS
	      o $text
		- The tested string.

RETURN VALUES
	Returns TRUE if every character in the string $text is a decimal digit, FALSE otherwise.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.1.0	|						    |
       |	|						    |
       |	|  Before  PHP	5.1.0,	this function returned TRUE |
       |	| when $text was an empty string.		    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES
       Example #1

	      A ctype_digit(3) example

	      <?php
	      $strings = array('1820.20', '10002', 'wsl!12');
	      foreach ($strings as $testcase) {
		  if (ctype_digit($testcase)) {
		      echo "The string $testcase consists of all digits.
";
		  } else {
		      echo "The string $testcase does not consist of all digits.
";
		  }
	      }
	      ?>

	      The above example will output:

	      The string 1820.20 does not consist of all digits.
	      The string 10002 consists of all digits.
	      The string wsl!12 does not consist of all digits.

       Example #2

	      A ctype_digit(3) example comparing strings with integers

	      <?php

	      $numeric_string = '42';
	      $integer	      = 42;

	      ctype_digit($numeric_string);  // true
	      ctype_digit($integer);	     // false (ASCII 42 is the * character)

	      is_numeric($numeric_string);   // true
	      is_numeric($integer);	     // true
	      ?>

NOTES
       Note

	       This function expects a string to be useful, so for example passing in an integer may not return the expected result. However, also
	      note that HTML forms will result in numeric strings and not integers. See also the types section of the manual.

       Note

	       If an integer between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative val-
	      ues have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string  contain-
	      ing the decimal digits of the integer.

SEE ALSO
       ctype_alnum(3), ctype_xdigit(3), is_numeric(3), is_int(3), is_string(3).

PHP Documentation Group 													    CTYPE_DIGIT(3)