(PHP 4 >= 4.0.4, PHP 5)
ctype_alpha — Check for alphabetic character(s)
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.
The tested string.
Returns TRUE if every character in text is a letter from the current locale, FALSE otherwise.
Example #1 A ctype_alpha() example (using the default locale) 以上例程会输出：
<?php
$strings = array('KjgWZC', 'arf12');
foreach ($strings as $testcase) {
if (ctype_alpha($testcase)) {
echo "The string $testcase consists of all letters.
";
} else {
echo "The string $testcase does not consist of all letters.
";
}
}
?>
The string KjgWZC consists of all letters.
The string arf12 does not consist of all letters.
Note:
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.