iOS Maths formula help

[jpitcairn]

I have created an app that calculated audio file sizes. The formula for this calculation is size = sample rate * number of channels * (bits per sample /8) * time in seconds.

So i have implented this formula using

int bSize = [channelNumber.text intValue] * [bitDepth.text intValue] / 8 * 
	[sampleRate.text intValue] * [trackLength.text intValue];

This forumla works for the most part but sometimes can give a negative answer. Any ideas why this is happening?

 

[jnic]

http://en.wikipedia.org/wiki/Integer_(computer_science)

It's probably wrapping. Maybe try an unsigned long long? Beyond that you'll need a library to handle very big numbers, such as OpenSSL's BN.