Character Menu Function

Mistro116@yahoo.com · 11-06-2005, 03:58 PM

I'm trying to write a reusable, keyword, reusable, function that I could use that will detect for valid input of a menu that only uses characters.

For instance:

If the menu choices are S, G, and Q, I would write a menu function that will accept valid input as only: S, s, G, g, and Q, q.

I wanted to write a function similar to:

Code:

int GetValidInt(int min, int max) { /* is set greater than max so the loop will be entered*/ int input = max + 1; /* Loop assures valid input */ while( input < min || input > max ) { printf("Please enter an integer between"); printf(" %d and %d.\n", min, max); scanf("%d", &input); } return input; }

However, the S, G, and Q are not next to each other. Is there a way to do this without simply writing something like if menuchoice != S, G, Q, etc...

Maybe with ascii values???

Someone recommended using an array of characters? How exactly would I do this?

Thanks.

Mistro116

Wim Sturkenboom · 11-06-2005, 11:06 PM

May I suggest that you put some newlines in your code-block. The reply button falls of the screen (and that hurts

)

Code:

int GetValidInt(int min, int max) {
/* is set greater than max so the loop will be entered*/
int input = max + 1; /* Loop assures valid input */
while( input < min || input > max ) {
  printf("Please enter an integer between");
  printf(" %d and %d.\n", min, max);
  scanf("%d", &input);
}
return input;

Now I can read it as well

With regards to the question:

Code:

/*
 * prompt user for input and validate
 * in:   prompt
 *        valid characters
 * return:
 *        validated input
*/
char GetValidChar(char *prompt, char *validchars) {
char input;
int valid=0;
while(1) {
  // prompt user for input
  printf("%s:",prompt);
  ch=get_input();  // use your input function here

  // check input here
  for(cnt=0;cnt<strlen(validchars);cnt++)
  {
    if(input==validchars[cnt])
    {
       valid=1;
       break;
    }
  }

  if(valid)
  {
    return input;
  }
  return 0;
}

Call with something like

Code:

ch=GetValidChar("valid input is AaBcdQq","AaBcdQq");

To make the function universal (and in the good *nix tradition), it does differentiate between lowercase and uppercase.
So in your example you have to pass S, s, G, g etc in validchars.