(PHP 4 >= 4.0.4, PHP 5)
ctype_cntrl — Check for control character(s)
Checks if all of the characters in the provided string, text, are control characters. Control characters are e.g. line feed, tab, escape.
The tested string.
Returns TRUE if every character in text is a control character from the current locale, FALSE otherwise.
Example #1 A ctype_cntrl() example 以上例程会输出：
<?php
$strings = array('string1' => "
", 'string2' => 'arf12');
foreach ($strings as $name => $testcase) {
if (ctype_cntrl($testcase)) {
echo "The string '$name' consists of all control characters.
";
} else {
echo "The string '$name' does not consist of all control characters.
";
}
}
?>
The string 'string1' consists of all control characters.
The string 'string2' does not consist of all control characters.
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.