PHP ctype_cntrl() Function (With Examples)

In this tutorial, we will learn about the PHP ctype_cntrl() function with its usage, syntax, parameters, return value, and examples. By IncludeHelp Last updated : December 31, 2023

PHP ctype_cntrl() function

The ctype_cntrl() function is a character type (CType) function in PHP, it is used to check whether a given string contains all control characters or not.

Note

Though control characters are unprintable character i.e. they cannot be represented in the string format if we represent they may display like symbols. So, we can provide the escape sequences in the string by following with forwarding slash (\), we can also provide the control character’s ASCII code in the range of hexadecimal values from 0x00 to 0x1f and 0x7f (Del).

To assign characters to value ASCII format (hexadecimal value), we use \x with the value.

Syntax

The syntax of the ctype_cntrl() function:

ctype_cntrl(string) : bool

Parameters

The parameters of the ctype_cntrl() function:

string: An input string.

Return Value

The return type of this method is bool, it returns true if all characters of the given strings are control characters (like, a newline character, tab character, escape character etc). Else it returns false.

Sample Input/Output

Input: "\r\n"
Output: true

Input: "\t\x12"
Output: true

Input: "\x00\x12\x1f\x7f"
Output: true

Input: "Hello123"
Output: false

PHP ctype_cntrl() Function Example

<?php
    $str1 = "\r\n";
    if(ctype_cntrl($str1))
        echo ("str1 contains all control characters.\n");
    else
        echo ("str1 does not contain all control characters.\n");
    
    $str2 = "\t\x12";
    if(ctype_cntrl($str2))
        echo ("str2 contains all control characters.\n");
    else
        echo ("str2 does not contain all control characters.\n");

    $str3 = "\x00\x12\x1f\x7f";
    if(ctype_cntrl($str3))
        echo ("str3 contains all control characters.\n");
    else
        echo ("str3 does not contain all control characters.\n");        

    $str4 = "\r \n"; //space is there 
    if(ctype_cntrl($str4))
        echo ("str4 contains all control characters.\n");
    else
        echo ("str4 does not contain all control characters.\n");

    $str5 = "Hello123"; //alphabets & digits are there
    if(ctype_cntrl($str5))
        echo ("str5 contains all control characters.\n");
    else
        echo ("str5 does not contain all control characters.\n");                
?>

Output

The output of the above example is:

str1 contains all control characters.
str2 contains all control characters.
str3 contains all control characters.
str4 does not contain all control characters.
str5 does not contain all control characters.

To understand the above example, you should have the basic knowledge of the following PHP topics:

PHP ctype_graph() Function