• Makefile # Makefile for I/O
• infile.dat 23 45 56
• sumthree.cpp Reads three numbers from the file infile.dat, sums the numbers, and writes the sum to the file outfile.dat.
• sumthree2.cpp reads three numbers from the file infile.dat, sums the numbers, and writes the sum to the file outfile.dat. checks if file is opened successfully
• sumthree3.cpp Reads three numbers from the file specified by the user, sums the numbers, and writes the sum to another file specified by the user. mixes console I/O and file I/O