096-swap-case

Swap Case

Challenge Description:

Write a program which swaps letters' case in a sentence. All non-letter characters should remain the same.

Input sample:

Your program should accept as its first argument a path to a filename. Input example is the following

Hello world!
JavaScript language 1.8
A letter

Output sample:

Print results in the following way.

hELLO WORLD!
jAVAsCRIPT LANGUAGE 1.8
a LETTER