A temporary file can be created, although some people do say they have problems with this. Is there any reason you cannot just keep the second part in ram until you are ready for the first? Otherwise, can you work out the size needed for the first part and leave that section of the file blank to come back to fill in later on. This would eliminate the needs of the temporary file.

A temporary file can be created, although some people do say they have problems with this, i personally have used them with no issues. Using the platform functions to obtain a temporary file is the best option. Dont assume you can write to c:\ etc on windows as this isnt always possible. Dont assume a filename incase the file is already used etc. Not using temporary files correctly is what causes people problems, rather than temporary files being bad

Is there any reason you cannot just keep the second part in ram until you are ready for the first? Otherwise, can you work out the size needed for the first part and leave that section of the file blank to come back to fill in later on. This would eliminate the needs of the temporary file.