assertion error mfc

Hi

I am getting an assertion error

cBuffer,iSizeOfBuffer,dValue,iDigits)

when iSizeOfBuffer = 10, dValue = 0.057632339906428, iDigits = 2

I do not understand why I am getting an error. I am using VS2012 pro and developing an MFC app. I expected cBuffer = "0.05". If I change iSizeOfBuffer  = 20, then there is no error.

another related issue:

_gcvt_s would normaly return an error code but does not when there is an assertion error. I was hoping to trap the error if an assertion error arose.

Any help gratefully appreciated.