Just found a piece of my code that had one original typo in it.
$msg = "Some text"; $msg .= " some more text"; $msg .+ " yet more text!"; $msg .= " last text";
.+ that should be
.=. What surprises me is that the code ran without producing any error, warning or notice and the output was:
Some text some more text last text
I was wondering why it did that. I know full well what
+= are but how is
.+ interpreted especially since there is no equal sign.
.+ operator, so that is
. followed by
You’re building an expression that consists of
$msg concatenated with the result of applying unary
" yet more text!" (which is
0 due to the cast to integer) … and then discarding the whole thing because you’re not doing anything with the result.
$msg .+ " yet more text!"; $msg . +" yet more text!"; // 1. PHP doesn't care about the spacing $msg . 0; // 2. Conversion to int from unary `+` $msg . "0"; // 3. Coersion to string for concatenation // 4. Nothing done with value
It’s perfectly valid; it just doesn’t do anything useful.
+ gets interpreted as a unary plus. PHP casts the string into an integer with the value 0 and concatenates it with
$msg. However you do not assign
$msg anything on that line, so
$msg won’t be changed.
This works because the
. is the concatenation operator, and
+ is the addition operator.
The line got interpreted like this:
$msg . (+" yet more text!");
+" yet more text!" converts the string to an int (
0 in this case as when PHP converts a string to an int, it stops at the 1st non-number character). It then concated the
$msg, and ignored the result.