Binary Calculations

[swindonshaun]

Hello there folks,

 

This is my first time posting to such a forum, so please be gentle with me!

 

What I am trying to do is write a script which represents the days of the week as binary (7 bits, each representing one day).

 

I can do this fine. My problem comes when I want to apply the ~ (bitwise NOT operator). It turns it into a 32 bit number, but it gets the desired result at the end of the number e.g.

 

In: 1100000

Out: 11111111111111111111111110011110

 

I have been looking high and low to see if I am doing something wrong. I have cast the variables as (int).

 

I think I understand why it behaves like this, and thought I had come up with a solution, which involving ANDing the output to 0000..1111 (25 zeroes and 7 ones), but the result is always 0. What am I doing wrong? Is there some way of declaring a number as binary as you would with hexadecimal?

 

Many thanks and apologies if this is a dumb question.

 

Shaun

[Daniel0]

It turns it into a 32 bit number

 

It already was.

 

Is there some way of declaring a number as binary as you would with hexadecimal?

 

No, but you can just write it in base 8, base 10 or base 16, which PHP has a syntax for. Internally in memory any number is stored as binary regardless, so the base n expansion you use when displaying it is irrelevant.

[corbin]

If this were a lower level language, you could use a byte (8 bits) instead of an int (32 bits)....

 

 

But anyway, you could always use either & or << to break it back down to 7 bits (padded with zeros).

[roopurt18]

And it with 0x000000ff

[ignace]

And it with 0x000000ff

 

By that he means:

 

$number & 0x000000FF

 

Just in case you wouldn't know what he means with "and it"