Adding string with number in php

Question

$a = "3dollars";
$b = 20;
echo $a += $b;
print($a += $b);

Result:

23
43

I have a question from this calculation.$a is a string and $b is number.I am adding both and print using echo its print 23 and print using print return 43.How is it

Answer 1

It casts '3dollars' as a number, getting $a = 3.

When you echo, you add 20, to $a, so it prints 23 and $a = 23.

Then, when you print, you again add 20, so now $a = 43.

Answer 2

The right way to add (which is technically concatenating) strings is

$a = 7;
$b = "3 dollars";
print ($a . $b);  // 73 dollars

The + operator in php automatically converts string into numbers, which explains why your code carried out arimethic instead of concatenation