Thank you everyone for your help!
I implemented a functional global variable on the LabView side and this has achieved the result I was looking for. A TCP connection would require more change to the C code than I would like to make and I also have no experience programming in C using TCP. Thank you for the suggestion and resources related to it. I will hold onto them for future reference.
Felix -- The LabView program will always be running and checking for a change in the value. It will have to react and carry out the rest of the procedures when it is indicated of a change. The C program will be called by a separate program and will only run when it is called and won't close until it receives the results from LabView. It's a process that has to be this way for the time being.
