I saw your code. Lot of variables used. Some lines can be cut down.But for timebeing let us have the same and discuss.Have you noticed this in your code;

printf("%d ", inputChar[e] + mod);

You are adding the char with a value but this affects only the display. The value stored in the array will not get changed to the sum.

for example: if I enter 'a' and mod as 20- it prints as 97+20=117 but still the value of the array remains only 97. it should be changed to 117 which only will then deduct the mod while you decode. Or else you will not get the required answer.

Have you heard of cryptography? It means translating plain text into scrumbled text in order to make the text unintelligible to unauthorised persons who view it. By the example encoding and decoding your objective may be that.

"Ceaser" is said to be the first in the list of using cryptography-so his algorithm of crytography is said to be 'Ceaser Cipher'. Nothing to worry. You have got many new algo. now. You can find more information about these in our dicussion forum or in google.

Chokks