See the PHP Handbook today with this passage:
"When dealing with the arithmetic operations of character variables, PHP inherits the Perl habit, not the C. For example, in Perl $a = ' Z '; $a + +; will turn $a into ' AA ', while in C, a = ' Z '; a++; Will turn a into ' [' (the ASCII value of ' Z ' is 90, ' [' ASCII value is 91). Note that character variables can only be incremented, cannot be decremented, and only plain letters (A-Z and A-Z) are supported. Increment/Decrement Other character variables are not valid and the original string does not change. ”
Other words:
Copy CodeThe code is as follows:
for ($i = ' A '; $i <= ' Z '; $i + +) {
echo $i;
if ($i = = ' ZZZ ') Die ();
}
The result is: Abcdefghijklmnopqrstuvwxyzaaabacadaeafagahaiajakalamanaoapaqarasataua .....
There are also string variables that cannot be decremented:
Copy CodeThe code is as follows:
$a = ' Z ';
-$a;
echo $a; Z
This also shows that the $a++ or + + $a, can not be $a = $a + 1; to explain
Copy CodeThe code is as follows:
$a = $b = ' Z ';
$a = $a + 1;
echo $a; 1
+ + $b;
Echo $b; Aa
http://www.bkjia.com/PHPjc/733056.html www.bkjia.com true http://www.bkjia.com/PHPjc/733056.html techarticle today, I see this passage in the PHP Manual: "When dealing with the arithmetic of character variables, PHP follows the habit of Perl, not C." For example, in Perl $a = ' Z '; $a + +; To put a.
