Convert a digit char to an int (same az the char) in c++

Question

I have an array that is char and all of them are numbers but in type of Char means:

myArray = ['5','6','8','9','10',....]

for example i wnat to add two of them.i must to convert them to integer and then add them together but using:

(int)myArray[1]+(int)myArray[2]

give a wrong answer. what is the function or the correct way for doing this?

@ThomasMatthews Yes I've seen it (tried). This is something I never tried before, I was surprised :). But I'll do better removing the comment :D — Jekyll, Nov 21 '13 at 22:21

score 5 · Answer 1 · edited May 23 '17 at 11:56

5

For ASCII digit chars from '0' - '9', one can substract the value of '0', since their values are contiguous:

char digit = '7' ; //any char, from '0' ... '9'
int value = digit - '0';

edited May 23 '17 at 11:56

Community

answered Nov 21 '13 at 20:27

Sam

1

For **all** encodings this is required. It's just about the only thing that's portable across encodings. – Pete Becker Nov 22 '13 at 18:59
@Pete Becker : Thank you for pointing that out. I've read up a bit, starting at the link I added. Until now, I never questioned the portability of my code regarding alphanumeric ranges. – Sam Nov 22 '13 at 19:34
I usually thump people for making ASCII-centric assumptions, so I appreciate your caution. – Pete Becker Nov 22 '13 at 20:35

score 1 · Answer 2 · answered Nov 21 '13 at 20:37

1

You can use the function atoi, for example:

char str[] = "122";
int i = atoi(str);

Notice that you must use the double quotes (") for strings. The single quotes (') work only for characters.

Also, you must add this include:

#include <cstdlib>

answered Nov 21 '13 at 20:37

jdc

2 Answers2