wrap around alphabet??

[Jeffrey Barrett]

hello, i'm working on a decoder program that lets the user input a key
(integer between 0 and 26) and then subtracts that number from a given
letter to produce a decoded message. for example, 'Y' - 12 = 'M'. My
problem is I would like the program to "wrap around the alphabet" when
it subtracts the key from the original letter. Ex. 'B' - 5 = 'W'.
this must work for lower and uppercase letters. any help would be
greatly appreciated.

 

[Thomas Matthews]

hello, i'm working on a decoder program that lets the user input a key
(integer between 0 and 26) and then subtracts that number from a given
letter to produce a decoded message. for example, 'Y' - 12 = 'M'. My
problem is I would like the program to "wrap around the alphabet" when
it subtracts the key from the original letter. Ex. 'B' - 5 = 'W'.
this must work for lower and uppercase letters. any help would be
greatly appreciated.

Use your favorite search engine for "ROT-13".

--
Thomas Matthews

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[Jack Klein]

hello, i'm working on a decoder program that lets the user input a key
(integer between 0 and 26) and then subtracts that number from a given
letter to produce a decoded message. for example, 'Y' - 12 = 'M'. My
problem is I would like the program to "wrap around the alphabet" when
it subtracts the key from the original letter. Ex. 'B' - 5 = 'W'.
this must work for lower and uppercase letters. any help would be
greatly appreciated.

char upper_case [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ";

Think about it, very useful in both directions.

 

[Jeffrey Barrett]

Try something like

#define AlphaWrap(c, n) ((c)-(n)<'A'?(int)'Z'+1+(c)-'A'-(n)c)-(n))

thanks for the help

im very new to c programming, could you explain what the c and n
variables would be?

thanks

 

[Martin Johansen]

Try something like

#define AlphaWrap(c, n) ((c)-(n)<'A'?(int)'Z'+1+(c)-'A'-(n)c)-(n))

 

[Richard Bos]

Try something like

#define AlphaWrap(c, n) ((c)-(n)<'A'?(int)'Z'+1+(c)-'A'-(n)c)-(n))

You've tried this using EBCDIC, I suppose? Funny results, what?

Richard

 

[Allan Bruce]

Martin Johansen <[email protected]> wrote in message

thanks for the help

im very new to c programming, could you explain what the c and n
variables would be?

thanks

It appears to be the char you want to encode, and the number of places to
shift for your encoding. e.g. to encode 'M' 12 spaces, then use
AlphaWrap('M', 12);
Allan