Ctype 函数
PHP Manual

ctype_digit

(PHP 4 >= 4.0.4, PHP 5)

ctype_digit — Check for numeric character(s)

说明

bool ctype_digit ( string $text )

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

参数

text

The tested string.

返回值

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

更新日志

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

范例

Example #1 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";
    }
}
?>

以上例程会输出：

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() 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
?>

注释

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:

如果给出一个 -128 到 255 之间(含)的整数, 将会被解释为该值对应的ASCII字符 (负值将加上 256 以支持扩展ASCII字符). 其它整数将会被解释为该值对应的十进制字符串.

参见

Ctype 函数
PHP Manual