php - 字符串的增量行为 - PHP 复活节彩蛋？

Question

$var = 'test_1';
var_dump(++$var); // string(6) "test_2" 

$var2 = '1_test';
var_dump(++$var2); // string(6) "1_tesu"

$var3 = 'test_z';
var_dump(++$var3); // string(6) "test_a"

$var4 = 'test_';
var_dump(++$var4); // string(5) "test_"

很明显，如果最后一个字符是数字，则在字符串上使用递增运算符会增加数字，如果最后一个字符在字母表中，则增加字母，然后重置为一次 z，并且没有对非字母数字字符的影响。

这是许多脚本语言所期望的标准功能，还是我只是找到了一个 PHP 彩蛋？

Answer 1

PHP follows Perl's convention when dealing with arithmetic operations on character variables and not C's. For example, in PHP and Perl $a = 'Z'; $a++; turns $a into 'AA', while in C a = 'Z'; a++; turns a into '[' (ASCII value of 'Z' is 90, ASCII value of '[' is 91). Note that character variables can be incremented but not decremented and even so only plain ASCII characters (a-z and A-Z) are supported. Incrementing/decrementing other character variables has no effect, the original string is unchanged.

-> http://php.net/manual/en/language.operators.increment.php