Subj : Any C programmers out there?
To   : Sarah Nunez
From : George White
Date : Thu Feb 08 2001 03:40 pm

* Replying to a message in : OS2

Hi Sarah,

On 06-Feb-01, Sarah Nunez wrote to All:

Over in OS2 you asked:

 SN> Off-topic request:

 SN> I need someone to give me some ideas on how to make a case
 SN> statement respond to letters as well as numbers.  (Plain vanilla
 SN> ANSI C.)  Please contact me privately at the email address below

The easy way is (extract from working code):

int     character;

/* The character is input into a char array called 'buffer' */

character = buffer[0] | 0x20;   /* Lower case ASCII characters */
if ((character >= '0') && (character <= '9'))
    character -= '0';           /* Numbers to 0 - 9 */
else
if (character >= 'a')
    character -= 0x57;          /* ASCII alpha to 0x0a et sequa */
else
    character = 0x10;           /* Or other default behaviour */
                                /* as required by the application */
        switch (character)
    {
    case        0x00:
        character = status_display (vdu,&buffer[1],24,FALSE);
        break;
    case        0x01:
        character = operational_display (vdu);
        break;
    case        0x02:   /* Lost/Damaged cards */
        /* etc */
        break;
    default:
        ;               /* Ignore anything else */
    }                   /* End switch statement */

How does it work?
First I or the character with 0x20 - this has no effect on the numbers
and converts letters to lower case.
Then I offset the numbers (0x30 to 0x39) to run from 0x00
otherwise I convert all lower case letters to run from 0x0A.
Any other characters are converted to a default value (in my case 0x10
because I only use 0-9 and the letters a-f) if you want all the alpha
characters this would be 'z' - 0x56 (I'm too lazy to work it out at
this time of night).
Then I have a value in 'character' which runs from 0 to my upper
switch limit, and off we go :-).

George

--- Terminate 5.00/Pro 
 * Origin: A country point under OS/2 (2:257/609.6)

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