do while loop parameters are not working

[melodia]

Hi I'm just wondering if anyone can tell me if there is something wrong with the way I am using the do while loop in my function GetIntInput().

This is a part of my program for tic tac toe. It compiles fine and runs but the problem I have is that my condition that the user and computer cannot place thier character 'X' or 'O' in the array at a location that doens't have ' ' in it ( I pound defined ' ' to be EMPTY)

But when the program executes the user can write over his own character and the computers. I highlighted the loop I think is the cause of the problem but I don't see why it isn't working.

Any thoughts??

Thank you!

/*******************************************************************************
********************************************************************************
This function is for the users turn
*******************************************************************************/
void userturn(char TTTboard[])
{
     int SquareNumber;     /*Number corresponding index array (TTTboard[])
     SquareNumber=GetIntInput(TTTboard);
     
     writetoboard(TTTboard, SquareNumber,USER); 
     DisplayTTTBoards(TTTboard);
}

/*******************************************************************************
********************************************************************************
 This function gets a valid integer input from the user.
 PRE: User has been prompted to enter an integer and min <= max.
 POST: an integer value, i, entered by user is returned, where min <= i <= max.    
*/

int GetIntInput(char TTTboard[])
{
    
    int i;
     
    do
    {
       printf("\n\nPlease enter number of the square you would like to place your 'O' in:");
       while(scanf("%i", &i) != 1)
   /* get rid of the characters that were entered */
       {
       clearInputStream();
       printf("\nThat is not valid. Please enter a valid location on the board: ");
 
       }
     

      /* clear the input stream again, in case extra characters after the integer
      were entered */
       clearInputStream();

     }while(ValueInRange(i,MIN,MAX)==FALSE && TTTboard[i]==COMPUTER && TTTboard[i]==USER);
        
       
       
                   return i;
          
} 

/*******************************************************************************
********************************************************************************
 This function determines if a value is within a range.
 PRE: min <= max and value is defined
 POST: returns true if min <= value <= max, and false otherwise.    
*******************************************************************************/

int ValueInRange(int value, int min, int max)
{
    if(min <= value && value<= max)
   
           return TRUE;
    else
              
           return FALSE;
   
}

[quzah]

Your value-in-range check is wrong.

value is in range if it's >= min, and <= max.


Quzah.

[rags_to_riches]

 TTTboard[i]==COMPUTER && TTTboard[i]==USER

Can both of those conditions ever be true at the same time?

[melodia]

Your value-in-range check is wrong.

value is in range if it's >= min, and <= max.


Quzah.

I'm not sure I understand how that is wrong? Doesn't it mean the same thing? Changing it to that wouldn't change the program when you compile it would it?

min=<value<=max is what i essentially have coded

and isn't that the same as:

value>=min and value <=max?



I'm still not sure why the condition that the array can only have EMPTY at a specific index to be able to write to it doesn't work.

[melodia]

Quzah,

Thanks for the reply! I'm just not sure how that would effect the function, could you clarify?

-melodia

[melodia]

Thank you rags_to_riches

 TTTboard[i]==COMPUTER && TTTboard[i]==USER

Can both of those conditions ever be true at the same time?

Exactly! I was wondering the same thing, they can't be the same, I thought about that but wasn't sure how I can make that work. Can I say:


}while(ValueInRange(i,MIN,MAX)==FALSE && TTTboard[i]==COMPUTER || TTTboard[i]==USER);

I think Itried this before but it didn't work. Should it work or would I have to change the condition completely somehow?

I also tried

}while(ValueInRange(i,MIN,MAX)==FALSE && TTTboard[i]!=EMPTY);


I pound defined EMPTY to be ' ' and the array is initalized to only contain ' ' until the user or computer enters in a character

[melodia]

I've tried all three ways and still the user can override any memory location in the array even if it already has an 'o' or 'x' in it. I cannot figure out why this loop control doesn't work. Help would be really appreciated

/*******************************************************************************
********************************************************************************
 This function gets a valid integer input from the user.
 User is been prompted to enter an integer and min <= max.
 It will repeat asking for input while the value is in the correct range and the memory location on board is not empty.
 POST: an integer value, i, entered by user is returned, where min <= i <= max.    
*/

int GetIntInput(char TTTboard[])
{
    
    int i;
     
    do
    {
       printf("\n\nPlease enter number of the square you would like to place your 'O' in:");
       while(scanf("%i", &i) != 1)
   /* get rid of the characters that were entered */
       {
       clearInputStream();
       printf("\nThat is not valid. Please enter a valid location on the board: ");
 
       }
     

      /* clear the input stream again, in case extra characters after the integer
      were entered */
       clearInputStream();

     }while( TTTboard[i]!=EMPTY && ValueInRange(i,MIN,MAX)==FALSE);
        
       
       
                   return i;
          
} 


/*******************************************************************************
********************************************************************************
 This function determines if a value is within a range.
 PRE: min <= max and value is defined
 POST: returns true if min <= value <= max, and false otherwise.    
*******************************************************************************/

int ValueInRange(int value, int min, int max)
{
    if(min <= value && value<= max)
   
           return TRUE;
    else
              
           return FALSE;
   
}

[anduril462]

I'm coming into this thread late, and haven't gone through all your code, but I did want to make a few comments.

Changing it to that wouldn't change the program when you compile it would it?

min=<value<=max is what i essentially have coded

and isn't that the same as:

value>=min and value <=max?

Yes, they are equivalent and your logic in ValueInRange is fine. As for the compiler changing it, it's hard to say. The resultant code will always behave the same, however the actual assembly code (and thus the ultimate binary) may be different. Depends on the compiler, but don't worry about it.

}while(ValueInRange(i,MIN,MAX)==FALSE && TTTboard[i]==COMPUTER || TTTboard[i]==USER);

Be careful of operator precedence here. Logical && has precedence over logical ||, so the code you wrote is equivalent to

while ((ValueInRange() == FALSE && TTTboard == COMPUTER) || TTTboard == USER)

Again, not having gone through your code, I can't be sure, but you may have wanted

while (ValueInRange() == FALSE && (TTTboard == COMPUTER || TTTboard == USER))

Notice the parentheses to force the || to evaluate first. Here is a link regarding operator precedences in C: C Operator Precedence Table.

I just realized, I think the do-while condition that I commented on above is not what you're after. I think you're after something like "get input while value is out of range, or the position is already occupied", which might look more like

do {
    ...
} while (ValueInRange() == FALSE || TTTboard == COMPUTER || TTTboard == USER);

Or, more simply

do {
    ...
} while (!ValueInRange() || TTTboard != EMPTY);

[quzah]

Quzah,

Thanks for the reply! I'm just not sure how that would effect the function, could you clarify?

-melodia

I misread you. I thought you were doing:

if( value <=min && value <= max )

instead of:

if( min <= value && value <= max )

I think the other poster was on the right track though.

while( inrange(...) == FALSE && ( board == player || board == cpu ) )

Or perhaps:

while( inrange() == false || board != empty )

Quzah.

[melodia]

Thank you both for replying to me! :-)

See this is why I am confused I've tried using both || and && but neither work. I've ended up leaving the code as:

}while( TTTboard[i]!=EMPTY && ValueInRange(i,MIN,MAX)==FALSE)

Sometimes I get confused by my boolean expressions though.
Just to clarify what I want GetIntInput() to do:

do all this

prompt for an integer
check if the user entered an integer

if the user did not enter a integer
prompt again for entry

if the user entered a integer
check if it is in the correct range (ValueInRange()) and check if the array TTTboard[] is empty or
not.

while ValueInRange() returns false and TTTboard[] is not empty


If the condition is && both conditions need to be true for it to return the integer the user entered

But if I use an || only one of the conditions needs to be true. This is wrong though because the entered integer could be in the correct range but the array at that index is already full.

Am I correct about the && and ||?

It's really confusing why this doesn't work. The program compiles perfectly fine but the condition that the memory location at the chosen index of the array must be empty to write to it is never met. Its so bizarre I feel like I'm going crazy.

[anduril462]

Your logic sounds fine to me. Try throwing in some debug output at the bottom of the do-while loop to make sure it's behaving like you expect, like so:

fprintf(stderr, "You entered %d\n", i);
fprintf(stderr, "MIN = %d, MAX = %d, ValueInRange(i, MIN, MAX) returns %s\n", MIN, MAX, ValueInRange(i, MIN, MAX) ? "TRUE" : "FALSE");
fprintf(stderr, "The current value of the requested cell is '%c'\n", TTTboard[i]);
fprintf(stderr, "TTTboard[i] != EMPTY evaluates to %s\n", TTTboard != EMPTY ? "TRUE" : "FALSE");