Begginer Question on Decairing Data Types

Development Boards MicroMod
1

Greetings,

I am using an Atmel to read the data off of a BMP085 pressure sensor, I downloaded the example code off of the SF site and am having trouble finding into on how a few of lines of code work.

b4 = (ac4 * (unsigned long) (x3 + 32768)) >> 15;
b7 = ((unsigned long) up - b3) * (50000 >> OSS);

I am familiar with declaring variables, ie unsigned long varX, but not this.

in the first line ac4 is an unsigned short and x3 is a long and b4 is an unsigned long, can someone please explain how to use these “partial declarations” within calculations or point me to some documentation (tricky to google things in parenthesis)… ?

Much appreciated!

2

They are “casts”. Get a good book on C, like K&R.

3

leon_heller:
They are “casts”. Get a good book on C, like K&R.

Great just needed the key word, thanks!