A sample introduction to the increment and decrement of PHP strings

This article mainly introduces the increment and decrement of string in PHP, need friends can refer to the following

Here's a quote from the PHP manual today: "When dealing with the arithmetic of character variables, PHP follows the custom of Perl, not C." For example, in Perl $a = ' Z '; $a + +; will turn $a into ' AA ', and in C, a = ' Z '; a++; The ASCII value of a ' [' (' Z '] is 90, and the ASCII value of ' [' is 91]. Note that character variables can only be incremented, cannot be decremented, and only plain letters (A-Z and A-Z) are supported. Increment/decrement of other character variables is invalid, the original string does not change. "That is to say: The code is as follows: for ($i = ' A '; $i <= ' Z ';  $i + +) {echo $i;  if ($i = = ' ZZZ ') Die ();    The result is: Abcdefghijklmnopqrstuvwxyzaaabacadaeafagahaiajakalamanaoapaqarasataua ......  There are also string variables that cannot be decremented: The code is as follows: $a = ' Z ';  --$a; echo $a;  Z This also illustrates that the $a++ or + + $a cannot be $a = $a + 1; To interpret the code as follows: $a = $b = ' Z ';  $a = $a + 1; echo $a;  1 + + $b; Echo $b; Aa