programming vigenre chiper in C....
 

need to write a programme that takes input from a text file then either encrypt or decrpyt it.
according to the ASCII code of this charecters
the user should give us his/her own keyword

then the program will save the output in a new file .

Example: Message: welcome home
Keyword: python
Cipher text: ç Þ à Ë Þ Û Õ ™ Ü × Ü Ó

w e l c o m e h o m e p y t h o n p y t h o n
w e l c o m e h o m e = 119 101 108 099 111 109 101 032 104 111 109 101
p y t h o n p y t h o n = 112 121 116 104 111 110 112 121 116 104 111 110
119 101 108 099 111 109 101 032 104 111 109 101
+ 112 121 116 104 111 110 112 121 116 104 111 110
--------------------------------------------------
231 222 224 203 222 219 213 153 220 215 220 211

231 222 224 203 222 219 213 153 220 215 220 211 = ç Þ à Ë Þ Û Õ ™ Ü × Ü Ó

You forgot to actually ask a question. "This is what I need to do for homework" is not a question.

Exactly which part of your requirements is giving your problems?

BTW, I like the choice of keyword. ;)