ctype_digit

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

Check for numeric character(s)

bool ctype_digit ( string $text )

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

Parameters:

text

The tested string.

Returns:

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

Changelog:

5.1.0

Before PHP 5.1.0, this function returned TRUE when text was an empty string.

Notes:

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.

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

Examples:

A ctype_digit() 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.\n";
    } else {
        echo "The string $testcase does not consist of all digits.\n";
    }
}
?>

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.

A ctype_digit() 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
?>