Effect of string starting with an ampersand

[NotionCommotion]

Why do I get the following results (specifically the second example)?  I thought it would be documented under https://www.php.net/manual/en/language.types.string.php, however, the word "ampersand" doesn't appear.  Also, looked at logical operators, but found nothing.  Thanks

function test(string $string){
    printf('%s %s %s 0'.PHP_EOL, gettype($string), $string, $string==0?'==':'!=');
}

test('123');
test('@123');
test('1@23');
test('123@');

Quote

string 123 != 0
string @123 == 0
string 1@23 != 0
string 123@ != 0

 

[Barand]

1 ) Why are you searching for "amprsand" when there are no ampersands (&) in your code.

2) the numeric value of a string is value of the numeric chars up to the first non-numeric character

echo intval('12@3');     // 12
echo intval('@123');     // 0

 

[NotionCommotion]

Thanks Barand,  No answer to #1, or at least no good answer.   Regarding #2, never realized such and appreciate letting me know.

[requinix]

Note that PHP 8 changed string <=> number comparisons.

[NotionCommotion]

20 hours ago, requinix said:

Note that PHP 8 changed string <=> number comparisons.

Thanks requinix,  Was going to comment on my reply to Barand that I felt PHP shouldn't be doing so, but didn't want to come off as whining.  Looks like I will get what I want after all

Quote

Comparisons between strings and numbers using == and other non-strict comparison operators currently work by casting the string to a number, and subsequently performing a comparison on integers or floats. This results in many surprising comparison results, the most notable of which is that 0 == "foobar" returns true. This RFC proposes to make non-strict comparisons more useful and less error prone, by using a number comparison only if the string is actually numeric. Otherwise the number is converted into a string, and a string comparison is performed.

 

[Barand]

20 minutes ago, NotionCommotion said:

Was going to comment on my reply to Barand that I felt PHP shouldn't be doing so

I hope you weren't planning on shooting the messenger.

[NotionCommotion]

Just now, Barand said:

I hope you weren't planning on shooting the messenger.

Never a messenger who provides accurate information (which it currently is)!