Question

I’d like to know, how to calculate integer values of strings in single quotes ' '.

My sample code is:

#include <stdio.h>

int main()
{
    int c = 'aA';
    int d = 'Aa';

    printf( "%d %d" , c, d);

    return 0;
}

And the output is:

24897 16737

What are those numbers? Is there any formula to calculate them ?

Answer 1

These are:

1. not strings!

2. multibyte integers, of which the value is implementation-defined, but it is usually calculated using this formula:

   integer value of 1st character multiplied by (2 << CHAR_BITS) + integer value of 2nd character

So, assuming your C locale uses ASCII and you have 8-bit bytes, 'aA' becomes

97 * 256 + 65

which is 24897.

Multicharacter literals are of type int.