Write a program that reads a telephone number from a file phnum.txt (available in lab folder) in
the form xxx-xxxx. The first three digits represent an area code and the next 4 digits represent
the phone number. Your task is to print these numbers into another file (outFile.txt) without any
space or ‘-’ between the area code and the number. Your program should define a function that
has input and output file streams as arguments.
If the phone number is 042-5610, the output should be 0425610.