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PHP | ctype_cntrl() Function

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The ctype_cntrl() is an inbuilt function in PHP which is used to check all the characters in string/text are control characters. Control characters are e.g. line feed, tab, escape.
Syntax: 
 

bool ctype_cntrl ( $str )

Parameters: This function accepts a single parameter $str. It is a mandatory parameter which specifies the string.
Return Value: It returns True if a string contains only control characters and False on failure.
Examples: 
 

Input: GeeksforGeeks
Output: No
Explanation: String (GeeksforGeeks) contains only the alphanumeric characters.

Input: \n\t
Output: Yes
Explanation: String (\n\t) contains only the control character.

Below programs illustrate the ctype_cntrl() function.
Program 1: 
 

php




<?php
// PHP program to check if a string has all
// control characters
 
$str1 = "GeeksforGeeks";
 
    if ( ctype_cntrl($str1))
     
        echo "Yes\n";
    else
        echo "No\n";
 
$str2 = "\n\t";
 
    if ( ctype_cntrl($str2))
     
        echo "Yes\n";
    else
        echo "No\n";
?>


Output: 

No
Yes

 

Program 2: Implementation of ctype_cntrl() function which takes input of an array of string that contains integers and special Symbol. 
 

php




<?php
// PHP program to check if a string has all
// control characters
  
$str = array(
    "Geeks",
    "Geeks space",
    "@@##-- /",
    "\n",
    "\t \r",
    "\r\t\n"
);
  
// Check the above strings by using
// ctype_cntrl() function
foreach ($str as $test) {
      
    if (ctype_cntrl($test))
        echo "Yes\n";
    else
        echo "No\n";   
}
  
?>


Output: 

No
No
No
Yes
No
Yes

 

References: http://php.net/manual/en/function.ctype-cntrl.php
 



Last Updated : 30 Jun, 2021
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