This program is used to count the number of occurences of each dipthong (two character pair) in a file.
The program read in the characters in batches of NMax which is defined as 10 in header.h.
you need to input the file name which you want to count the dipthong.Then you also need to give it a output file name.
The output is a list of the dipthongs and their counts  with the character code pair followed by a integer giving the number of occurences of that pair.
I test the the program on the same book as in HW7. The result is in "result.txt".And the time for counting is 0.02 Seconds.