Thread: ASCII and EBCDIC

EBCDIC is apparently still used in IBM mainframes, although ASCII is "tolerated" in that you can edit ascii files and the cpu has instructions for conversion. EBCDIC - Wikipedia

I would use int since character literals are ints in C anyway, and functions like getchar return an int.

Code:

#include <stdio.h>
#include <ctype.h>
 
int get_index(int ch)
{
    ch = toupper(ch);
    if (ch >= 'A' && ch <= 'I') return ch - 'A';
    if (ch >= 'J' && ch <= 'R') return ch - 'J' + 9;
    if (ch >= 'S' && ch <= 'Z') return ch - 'S' + 18;
    return -1;
}
 
int main()
{
    int ch;
    while ((ch = getchar()) != EOF)
        printf("%d\n", get_index(ch));
    return 0;
}

A switch might actually be faster.

Code:

int get_index(int ch)
{
    switch (toupper(ch))
    {
    case 'A': return 0;
    case 'B': return 1;
    }
    return -1;
}