Testing Multiple Conditions

Searched, couldn't find it.. I'm looking to simplify this:

if ((menuSelection != 'A') || (menuSelection != 'B') || (menuSelection != 'C') || (menuSelection != 'D') || (menuSelection != 'X'))

Can anyone help?

Thanks in advance..

Andrew

If it's continuous:
if (menuSelection >= 'A' && menuSelection <= 'X')

it's not :D but thanks. Anyone else?

oops.. sorry folks, it should be:

if ((menuSelection != 'A') && (menuSelection != 'B') && (menuSelection != 'C') && (menuSelection != 'D') && (menuSelection != 'X'))

you could put it into a small function:

Code:

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bool checkInput( const char& input )
{
    //perform if statement to make sure a valid character is entered.
    return true;
}

---

this kind of function is good if you are using the same menu more than once and need to frequently validate the input

Code:

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bool
 is_true(char ch) {
 
  switch(tolower(ch)) {

  case 'a': case 'x': case 'b' : case 't':
  return true;

  }

  return false;
 }

---

Thanks Guys...

Here's a doozy of a compound boolean statement (its movement checking for a knight in my chess game):

Code:

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if((x2 == (x1 - 2) && y2 == (y1 -1)) || (x2 == (x1 - 2) && y2 == (y1 + 1)) ||
                (x2 == (x1 -1) && y2 == (y1-2)) || (x2 == (x1 - 1) && y2 == (y1 + 2)) ||
                (x2 == (x1 + 1) && y2 == (y1 -2)) || (x2 == (x1 + 1) && y2 == (y1 + 2)) ||
                (x2 == (x1 + 2) && y2 == (y1 - 1)) || (x2 == (x1 + 2) && y2 == (y1 + 1)))

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.... perhaps you should implement it differently then :)

Quote:

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Originally posted by BMJ
.... perhaps you should implement it differently then :)

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hey, for my simple chess program it works. What would you suggest? :)

use a case statement, have switches for 'A' 'B' 'C' 'D' and 'X', and have the code under the

if ((menuSelection != 'A') || (menuSelection != 'B') || (menuSelection != 'C') || (menuSelection != 'D') || (menuSelection != 'X'))

be exectued in the default: thingy instead

Quote:

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Originally posted by moi
use a case statement, have switches for 'A' 'B' 'C' 'D' and 'X', and have the code under the

if ((menuSelection != 'A') || (menuSelection != 'B') || (menuSelection != 'C') || (menuSelection != 'D') || (menuSelection != 'X'))

be exectued in the default: thingy instead

---

Thats diferent than a compound if statement, though. What you've just proposed is a replacement for multiple if statements.

Quote:

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Originally posted by Captain Penguin
Thats diferent than a compound if statement, though. What you've just proposed is a replacement for multiple if statements.

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i made the assumption (wrongly i guess) that he would want to be processing entry for the valid keys at the same time that he elimiates bad entries

Quote:

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Originally posted by moi
i made the assumption (wrongly i guess) that he would want to be processing entry for the valid keys at the same time that he elimiates bad entries

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Hey whaddya know, that IS what he was doing. I sort of ignored his main post and concentrated on the phrase of the subject, "Testing multiple conditions". :)

Arrays come to mind...

Quote:

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Originally posted by Sebastiani
Arrays come to mind...

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Arrays? Not sure what you're meaning is here.

My program is very simple.. a class consisting of an 8x8 char array with '_''s as blank spaces and letters for pieces. The class has a Move() function which takes 4 arguments, x1, y1, x2, and y2. x1,y1 is the starting piece and x2,y2 is the destination. The function checks the coordinates to make sure it is a valid move, and in the if() statement I posted above, those are when the move is valid for a knight.

well i have also implemented the game in C... I used an array of 64 to make it simpler.. 8 x 8 has a problem of manuplating validity..



this is how i dod it.. conside there is an array of array[64].. now consider that the king is in the array[40] position.. no to get a valid move i check the move made like this...


consider i = 40;


now valid moves are

array[i+1];
array[i-1];
array[i-8];
array[i+8];
array[i-9];
array[i-7];
array[i+9];
array[i+7];

that is |'''''''|''''''''|'''''''''|
'''''''''''''x'''''''''''''''' |'''''''|''''''''|'''''''''|
''''''''''''''''''''''''''''''
where x is the king.. But this algorithm has a problem.. now conside that the king is in the 8th A8 then the position b1 also become a valid move.. i check this inside the loop... so instead of considering the blocks in this order

1 2 3 4 5 6 7 8
A ------------------------------>--------->
B--------------------------->----------->


i made it as
1 2 3 4 5 6 7 8
A ------------------------------>--------->|
B ---<---------------------<-------------<-|


so that problem is eliminated.. and for example if an component is above to move to a valid position say array[40]. then i check if there is any other pawns in that block.. i stored the position of all the pieces in an array called component[64]; so this holds the entire state of the chess board...



so if any doubts u r free to ask questions.... My game is not yet ready.. i am still workong on it.. i have problems in pecial moves like castling etc etc.. and my game is a 2 player game.. so no AI involved,, i am planin to implement one later.. for this i have thought of a pointing system where i can back track 2 levels(not that intlegent program but still...) and then allocating points to the white and black side.. but i will have to improve this...