Bitwise Negation

[m92g11]

I'm reading a book on PHP called Programming PHP. And in this book they mention the following line:

"If the operand is a string, the resulting value is a string the same length as the original, with each character in the string negated."

My question is how is a string negated. I'm lost. :queasy: any help?

Thanks in Advance
Michael

[bradgrafelman]

A string is nothing more than a collection of binary values interpreted as characters (such as ASCII).

Once you realize that, it should be simple to understand that negating a string is no different than doing bitwise negation.

[m92g11]

The string "hi" in the conversion from binary to ASCII is:
[FONT="System"]0110100001101001[/FONT]
If we where to use bitwise negation the string "hi" would look like:
[FONT="System"]1001011110010110[/FONT]
So basically this is how bitwise negation is handled? Everything is flip flopped in the binary representation?

[bradgrafelman]

m92g11 wrote:

So basically this is how bitwise negation is handled? Everything is flip flopped in the binary representation?

Well, yeah... that's the definition of negation. :p That or taking the binary number and XOR'ing it with n 1's (where n is the number of bits of the number you're trying to negate).

[m92g11]

okay cool thanks man 🙂 now its time to learn the logical operator XOR so i can understand what you just said. lol :p