In PHP why does range a-Z and a for loop applied to the alphabet produce different characters?

Question

I noticed there is two different behaviors in PHP when we increment the alphabet:

Range:

range('a', 'Z');

output:

["a","`", "_", "^", "]","\", "[","Z"]

Which correspond to the ASCII table and make sense to me.

But when we increment with a for loop:

$letters = [];
for($i = 'a'; $i !== 'Z'; $i++){
    $letters[] = $i;
}

output:

[ "a", "b", "c", "d", ..., "x", "y", "z", "aa", "ab", "ac", "ad", "ae", "af", ...]

Why is php suddenly stuck with the letters 'a-z' instead of using the ASCII table?

And how does work the range method for not using this behavior?

fixed, I did copy/paste the wrong output from my tests – Clément Baconnier Apr 30 '18 at 07:34 — Clément Baconnier, Apr 30 '18 at 07:34
Relevant: https://stackoverflow.com/q/14278603/2943403 – mickmackusa Apr 30 '18 at 07:37 — mickmackusa, Apr 30 '18 at 07:37

score 2 · Accepted Answer · answered Apr 30 '18 at 07:16

2

Just read the manual: http://php.net/manual/en/language.operators.increment.php

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 alphabets and digits (a-z, A-Z and 0-9) are supported. Incrementing/decrementing other character variables has no effect, the original string is unchanged.

answered Apr 30 '18 at 07:16

Thomas G

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Thanks, but this not really answering my question: Why is `range` doesn't return 'AA' too? Why is this different? – Clément Baconnier Apr 30 '18 at 07:26
`AA` is a string consisting of 2 single-byte characters. – mickmackusa Apr 30 '18 at 07:28
1

Because the Range() function is "plugged" on the ASCII table and the increment operator is not. There's no other answer. It is a design choice from PHP developpers. – Thomas G Apr 30 '18 at 07:29
From the range manual: _Note: Character sequence values are limited to a length of one. If a length greater than one is entered, only the first character is used._ – mickmackusa Apr 30 '18 at 07:34
Thanks Thomas G! Maybe one day, I will know what the reasons behind it. – Clément Baconnier Apr 30 '18 at 07:43
1

Advice: sometimes you have to not think too much about things and just accept them as they are – Thomas G Apr 30 '18 at 07:44
mickmackusa: my question is not: Why it's doesn't work, but why it works like that. – Clément Baconnier Apr 30 '18 at 07:44

In PHP why does range a-Z and a for loop applied to the alphabet produce different characters?

1 Answers1