i wonder how the operation of addition works in case of one value to be numeric and other to be string For Example:
echo $j = 1 + "stackoverflow";
I tried executing this expression, It outputs me 1.. Can someone explain me why the string is not involved in addition, if it is involved then why is it converted to 0?
stackoverflow starts with no digit so php takes it 0
1stackoverflow would be 1 because it starts with digit 1
If you do this PHP tries to parse the integer value of the string. In this case "stackoverflow" is parsed to 0.
You can see for yourself what the integer value of a string is by using intval().
intval("stackoverflow"); // = 0
intval("123stackoverflow"); // = 123
Play around with it to get used to it.
In the operation above, PHP will try to convert both operands to numbers. Therefore "stackoverflow" string is actually converted to number - 0 in this case. Why this happens is best described in this manual page - converting string to numbers. Note that
$j = 1 + "1stackoverflow"
will produce 2 as the result.
Because it tries to convert the string to integer, and then adds it tot the number. It's basically the same as echo $j = 1 + intval("stackoverflow");
If you want to concatenate the string to the number, you have to use the concatenation operator, that is the dot: echo $j . "stackoverflow"
