PHP char编码，＃== 0,0 == NULL，＃！= NULL

Question

I need to use a special character as a stop/break signal for my program. I was trying out '#' '&' '@' and kept on receiving errors.

After some messing around, I discovered that all characters including the ones above all had the numeric value 0! I did so by comparing their values with numerics, because at first I thought it used ASCII codes.

Wait a minute, that's not right, because NULL also equals to 0! But the characters definitely does not equal to NULL!

So, what kind of char coding does PHP use? Is it impossible to compare chars with numbers?

Thanks in advance!

Answer 1

I'm just assuming you're doing something like:

var_dump("#" == 0);
// bool(true)

When comparing to numbers, strings are cast into numbers to deal with situations like '123' == 123. The string '#', or in fact pretty much every non-numeric string, casts to 0.

That's why there's the === operator:

var_dump("#" === 0);
// bool(false)

Welcome to weakly typed languages.
http://www.php.net/manual/en/language.types.type-juggling.php