Question 2: Letter frequencies

A classical way to break a code is to look at the frequency of symbols appearing in encoded text. In English, the three most commonly appearing letters are e, t, and a, so, for a moderately long piece of text, frequency information gives a starting point to help crack some simple codes. Write a C++ program that reads in the text file input.txt and prints the frequency that each letter of the alphabet is used in its contents. The frequency of some letter is freq(x) := Count of x in input/Total number of all letters . Treat uppercase and lowercase symbols as identical and ignore all other characters.

Use char[]s for the strings, assuming that the input has lines of no more than 100 characters in length.