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ctype_alpha

(PHP 4 >= 4.0.4, PHP 5)

ctype_alpha -- Check for alphabetic character(s)

说明

bool ctype_alpha ( string text )

Checks if all of the characters in the provided string, text, are alphabetic. In the standard C locale letters are just [A-Za-z] and ctype_alpha() is equivalent to (ctype_upper($text) || ctype_lower($text)) if $text is just a single character, but other languages have letters that are considered neither upper nor lower case.

参数

text

The tested string.

返回值

Returns TRUE if every character in text is a letter from the current locale, FALSE otherwise.

范例

例子 1. A ctype_alpha() example (using the default locale)

<?php
$strings = array('KjgWZC', 'arf12');
foreach ($strings as $testcase) {
    if (ctype_alpha($testcase)) {
        echo "The string $testcase consists of all letters.\n";
    } else {
        echo "The string $testcase does not consist of all letters.\n";
    }
}
?>

上例将输出：

The string KjgWZC consists of all letters.
The string arf12 does not consists of all letters.

参见

ctype_upper()
ctype_lower()
setlocale()


add a note add a note User Contributed Notes
egypt at nmt dot edu
22-Nov-2003 09:16
Be careful with all of the ctype_* functions as they return true on the empty string, so the following code will execute forever.

(see also http://bugs.php.net/30945)

<?php
$string = "abc";
// infinite loop!
for($i = 4;ctype_alpha($string[$i]); $i++)
{
   print $i;
}
?>

so always check the length of the string before doing something like that. i.e.:

while($i < strlen($string) && ctype_alpha($string[$i]))
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ctype_alnum上一级ctype_cntrl