Thread: Loop with Scanf / switch statement causing weird output

creating a validation check to ensure the cards entered are correct. It works when the cards are entered correctly the first time. After an invalid entry, the cards store the default value in a switch statement and always cause an error...

Code:

 
#include <stdio.h>
#include <stdbool.h>

int main()
{
    int j, i, k, n = 5, check = 2;

    char hands[2][5];
    int nhands[2][5];
    int first_hand[5];
    int second_hand[5];
    int count[14];

   /* Loop until it is validated */
       while(check == 2){  
       printf("\nPlease enter a hand of 5 card poker for 2 players. Format HHHHH HHHHH\n");
    /* Get the cards */
       scanf("%c%c%c%c%c %c%c%c%c%c", &hands[0][0], &hands[0][1], &hands[0][2], &hands[0][3], &hands[0][4], &hands[1][0], &hands[1][1], &hands[1][2], &hands[1][3], &hands[1][4]);
     
   /* Change the char values to numerical values for easier testing */  
    for(j = 0; j<2; j++){
       for(i = 0; i<5; i++){
       switch(hands[j][i]){
         default  : nhands[j][i] = 15; break; 
         case 'A' : nhands[j][i] = 14; break;
         case 'K' : nhands[j][i] = 13; break;
         case 'Q' : nhands[j][i] = 12; break;
         case 'J' : nhands[j][i] = 11; break;
         case '0' : nhands[j][i] = 10; break;
         case '9' : nhands[j][i] = 9; break;
         case '8' : nhands[j][i] = 8; break;
         case '7' : nhands[j][i] = 7; break;
         case '6' : nhands[j][i] = 6; break;
         case '5' : nhands[j][i] = 5; break;
         case '4' : nhands[j][i] = 4; break;
         case '3' : nhands[j][i] = 3; break;
         case '2' : nhands[j][i] = 2; break; 
         
         }     
       }
    }
    
    for(k=0; k<14; k++){
        count[k] = 0;
        check = 1;
    }
    /* Checks for invalid card types entered */
    for(j = 0; j<2; j++){
       for(i = 0; i<5; i++){
           if(nhands[j][i] == 15){ 
               check = 2; 
               printf("You entered an invalid card, please retype your hand");
                   
                   /*debug */
                   for(j = 0; j<2; j++){
                         for(i = 0; i<5; i++){
                               printf("\ncard %d: %d", i+1, nhands[j][i]);
                         }
                   }
           }           
       }
    }
    /* Checks for more than 4 of the same card type */
    for(k = 0; k<14; k++){
          for(j = 0; j<2; j++){
                for(i = 0; i<5; i++){
                   if(nhands[j][i] == (k+2)){ count[k] = count[k] + 1; }
                } 
          }
          if( count[k] > 4) { 
              check = 2;
              printf("You entered too many of the same card, please retype your hand");                     
          }
          
    } 
}   
getch();
return 0;
}

Cprogramming.com FAQ > Flush the input buffer
scanf with %c reads every character, including newlines.
Most other format conversions skip over white space (including newlines).

It would be better if you used fgets() to read into a large buffer, then extracted what you wanted from the line in memory. It saves an awful lot of trying to tidy up the input stream.

You could call scanf(%c) one more time to eat the \n.

But you're still extremely dependent on the user cooperating with the input your program expects.

I hope your tutor gets around to fgets() pretty soon...

> default : nhands[j][i] = 15; break;
I would suggest you add something like

Code:

printf("Found bad character %c(%d)\n", hands[j][i], hands[j][i] );

so you can see exactly what you're getting.

And from that, perhaps figure out what input caused it.

You need to consume the newline then after you read the hand.

Code:

int readhands( char hand1[5], char hand2[5] )
{
    int rval = 0;
    printf( "Enter two hands in this format: CCCCC CCCCC\n" );
    rval = scanf( "%c%c%c%c%c %c%c%c%c%c%*[^\n]\n",
        &hand1[ 0 ], &hand1[ 1 ], &hand1[ 2 ], &hand1[ 3 ], &hand1[ 4 ]
        &hand2[ 0 ], &hand2[ 1 ], &hand2[ 2 ], &hand2[ 3 ], &hand2[ 4 ] );
    return rval == 10;
}

Something like that looks like it should work.


Quzah.