Description
bool 
ctype_cntrl ( string text)
     Returns TRUE if every character in text has
     a special control function, FALSE otherwise. Control characters are
     e.g. line feed, tab, esc.
    
     
例子 1. A ctype_cntrl() example 
<?php $strings = array('string1' => "\n\r\t", 'string2' => 'arf12'); foreach ($strings as $name => $testcase) {     if (ctype_cntrl($testcase)) {         echo "The string '$name' consists of all control characters.\n";     } else {         echo "The string '$name' does not consist of all control characters.\n";     } } ?>
 |  
 
       This example will output :
       The string 'string1' consists of all control characters.
The string 'string2' does not consists of all control characters.  |  
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