Parse error Unexpected (, expected , in php when assign content file to a static property

I have this class:

class MyClass {
  const DB_NAME  = "MyDb";

  const HOST = "localhost"; 

  const USER = "abcdef";

  const PASSWORD = "ghijklmn";


  public static $MyString = file_get_contents('file.txt');

}
?>

I have no idea what is wrong with file_get_contents ?

I cannot understand what is the error says ? Why ( is unexpected ?

I read the following articles but these don't help me to solve that error:

Parse error: syntax error, unexpected T_STRING in php

Parse error T_Variable

file_get_contents shows unexpected output while reading a file

Answer

It's because you have assigned expression to variable declaration. It can only use constants.

The workaround would be like this

class MyClass {
    ...
    public static $MyString;
    ...
}
MyClass::$MyString = file_get_contents('file.txt');