How to remove control characters from PHP string ?

0 0 1 minute read

Given a string that contains control characters. The task is to remove all control characters from a string. In ASCII, all characters having a value below 32 come under this category. Some of the control characters are given below:

S.NO	ASCII VALUE	Name	Symbol
1.	0	null (NUL)	“\0”
2.	9	horizontal tab(HT)	“\t”
3.	10	line feed(LF)	“\n”
4.	11	vertical tab(VT)	“\v”
5.	27	escape(ESC)	“\e”

Example:

Input: str = "\0\eGeeks\t\e\tfor\v\vGeeks"
Output: zambiatek

In this article, we will remove control characters from the PHP string by using two different methods.

Using General Regular Expression:
Using ‘cntrl’ Regex:

Using General Regular Expression: There are many regular expressions that can be used to remove all Characters having ASCII value below 32. Here, we will be using preg_replace() method.

Note: The ereg_replace() method is removed from PHP >= 7, so here we will be using preg_replace() method.

Program:

<?PHP  
  
// PHP program to remove all control  
// characters from string  
    
// String with control characters  
$str = "\eGeeks\t\tfor\v\vGeeks\n";  
    
// Using preg_replace method to remove all   
// control characters from string  
$str = preg_replace('/[\x00-\x1F\x7F]/', '', $str);  
    
// Display the modify string  
echo($str);  
    
?>  

Output:
```
zambiatek
```

Using ‘cntrl’ Regex: This can also be used to remove all control characters. And [:cntrl:] stands for all control character.

Program:

<?PHP  
  
// PHP program to remove all control  
// characters from string  
    
// String with control characters  
$str = "\eGeeks\t\tfor\vGeeks\n";  
    
// Using preg_replace method to remove all   
// control characters from string  
$str = preg_replace('/[[:cntrl:]]/', '', $str);  
    
// Display the modify string  
echo($str);  
    
?>  