CODEWITHSUNDEEP
csubtractionletters-and-numbers
JJJ
JJJ

Reputation: 43

subtracting letters in c

I would like to know how to "subtract letters" in C:
I mean, I have 2 letters, 'a' and 'c' and i want to execute 'c'-'a'='b' which is 3-1=2.
How is it possible to obtain the same behaviour in C?
I can conversion Letters->Numbers but how to manage the limited lenght of the alphabet? Thank you.

Upvotes: 2

Views: 23184

Answers (2)

twain249
twain249

Reputation: 5706

you can treat the letters as numbers and then add the letter 'a' back to normalize it

so

char c1 = 'a';
char c2 = 'c';
int diff = c2 - c1; //'c' - 'a' = 2
char ans = diff + 'a' - 1; //add 'a' and subtract 1 to normalize it

If you want the number difference just use diff from my answer (ans will give you the letter).

This will not wrap around so

'a' - 'b'

will result in -1 (or the character before a)

If you want to handle negatives with a wrap you have to check it 

int diff = c2 - c1;
char ans;
diff > 0 ? ans = diff + 'a' - 1 : 'z' + diff + 1;

This will give:

  1. 'z' for 'b'-'c'
  2. 'y' for 'b'-'d'

Upvotes: 7

RolandXu
RolandXu

Reputation: 3678

Are you looking this?

char a1,a2,a3;
a3 = a1 - a2 + 'a';

Upvotes: 0

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