問題描述

$var = 'test_1';
var_dump(++$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_"

很明顯，如果最后一個字符是數字，則在字符串上使用增量運算符具有增加數字的效果，如果最后一個字符在字母表中，則增加字母然后重置為一次 z，并且沒有對非字母數字字符的影響.

So apparently, using an increment operator on a string has the effect of increasing the digit if the last character is a number, increasing the letter and then resetting to a once z if the last character is in the alphabet, and has no effect on non alpha numeric characters.

這是許多腳本語言都期望的標準功能，還是我只是找到了一個 PHP 復活節彩蛋?

Is this a standard feature, expected in many scripting languages, or did I just find a PHP easter egg?

推薦答案

PHP 在處理算術運算時遵循 Perl 的約定在字符變量上而不是 C 的.例如，在 PHP 和 Perl 中 $a ='Z';$a++;把 $a 變成 'AA'，而在 C a = 'Z';一個++;變成'['('Z'的ASCII值為90，'['的ASCII值為91).注意字符變量可以增加但不能減少，即使如此僅支持純 ASCII 字符(a-z 和 A-Z).增加/減少其他字符變量沒有效果，原始字符串不變.

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

這篇關于字符串的增量行為 - PHP復活節彩蛋?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！