stdin + (ctrl+z), how i detect it?

Some days ago i came here asking about the CRC and other small things... well, that part of the project is ready and the CRC is working fine..

but at the end of the projct there is a small line of the text saying something like this: "If the user doen´t give us a file when invoquing the CRC we have to use the stdin to read the text that the user is tipyin, and then appply the CRC to that text. The user will finish typing when pressing CTRL+Z (^Z in the DOS console)"

How do I dettect the CTRL+Z when reading one char at time from stdin, it's beacause i've got to pass it on to another file to apply the CRC on this text....

And one smallest doubt, when I try to make some modules just not to include alll the project in only one, the computer doesn´t find them... (modules are one for the input, another for the output and one last having the CRC check), where do i have to put them? [I'm usin Bloodshed Dev C++] or how do i've got to do to specifie the address of the module in my PC when "including" them in the main modulE??

THANKS
fran

I just told you in your other post
http://cboard.cprogramming.com/showp...70&postcount=4