PHP code type transformation understanding

Question

Hello I'm start learning php, please help me understand code

$a = True.False;
echo $a;

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Result -> 1

But!

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$b = True.True;
echo $b;

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Result - > 11

why is this happening?

Answer 1

A boolean TRUE value is converted to the string "1". Boolean FALSE is converted to "" (the empty string). This allows conversion back and forth between boolean and string values.

From the manual: https://www.php.net/manual/en/language.types.string.php