Question

Consider

$foo = "abcdefg";

echo $foo[0]; //outputs a

So it seems like strings are like array of characters but then why

foreach($foo as $char)
{
echo $char;
}

does not work and gives following Warning ??

Warning: Invalid argument supplied for foreach() 

Answer 1

Adding string iteration support to foreach was discussed but declined. There were mainly two reasons for this decision:

• It makes applications harder to debug. Usually you don’t want to iterate over the characters of a string. You need that only very rarely. So if you do iterate over a string you probably just made a programming mistake – and PHP will tell you so. If string iteration were introduces this kind of error would be hard to catch.
• What is a “character”? Should PHP iterate over each single byte? Should it iterate over characters (which can be multiple bytes)? If so, what should it do if it encounters a malformed multibyte sequence? And where does it get the charset from?

To solve both problems there was a proposal to introduce a TextIterator, which you pass a string and a charset. That way you can’t accidentally iterate a string and the byte vs character problem doesn’t exist. I’m not sure though what the state of the TextIterator is currently.