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How to remove control characters from PHP string ?

  • Last Updated : 15 Apr, 2020

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.NOASCII VALUENameSymbol
1.0null (NUL)“\0”
2.9horizontal tab(HT)“\t”
3.10line feed(LF)“\n”
4.11vertical tab(VT)“\v”
5.27escape(ESC)“\e”

Example:

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

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:
    GeeksforGeeks

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); 
        
    ?> 
  • Output:
    GeeksforGeeks



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