在PHP中使用字符串

Question

Recently, I came across the need of going through a string to act on his letter

As far as I know, a string in PHP is represented as an array of bytes as stated in the doc.

Then I naturally wrote :

$str = 'Hello';
foreach ($str as $letter) {
   doMyThingsOnLetter($letter);
}

Sadly, I got an error saying me that I have provided foreach an invalid argument

I know that this work :

$str = 'Hello';
for($i = 0; $i < strlen($str); $i++) {
   doMyThingsOnLetter($str[$i]);
}

So here, $str is considered as an array but by a foreach we got an error for invalid argument (while it states in the doc it allows arrays)

So I wonder if there is some sort of different type of array for the representation of the string itself in PHP or is it only the way foreach handle array differently ?

PS: I know str_split() exist for this purpose but that's not my concern here

Answer 1

$str[$i] doesn't treat it as an array. This is just a shorthand notation for substr($str, $i, 1).

You can use str_split() to get an array of characters from a string:

foreach (str_split($str) as $letter)

From the documentation:

Characters within strings may be accessed and modified by specifying the zero-based offset of the desired character after the string using square array brackets, as in $str[42].