How to count the "white" correctly in mastermind guessing game in c?

Question

“White" is the checking of correct number at wrong position. But I don't know how to count it correctly.

#include "stdafx.h"
#include "stdlib.h" 
#include "time.h"

int _tmain(int argc, _TCHAR* argv[])
{
    int answer[4];
    int guess[4];
    int count = 0;

    srand(time(NULL)); 
    /*answer[0] = (rand() % 6)+1;
    answer[1] = (rand() % 6)+1;
    answer[2] = (rand() % 6)+1;
    answer[3] = (rand() % 6)+1;*/

    answer[0] = 3;
    answer[1] = 3;
    answer[2] = 5;
    answer[3] = 2;

    printf("%d %d %d %d\n", answer[0],  answer[1],  answer[2],  answer[3]);
    printf("          B W\n"); 

    do
    {
        int black = 0;
        int white = 0;
        count++;
        printf("Enter 4 numbers, this is your %d guess: ", count);
        scanf("%d %d %d %d", &guess[0], &guess[1], &guess[2], &guess[3]);
        printf("\n%d %d %d %d\n", guess[0], guess[1], guess[2], guess[3]);

        int g2[2][6];

        for (int a = 0;a < 4;a++)
            g2[0][a]=answer[a];

        for (int i = 0;i < 4;i++)
            g2[1][i]=guess[i];

        if (answer[0]==guess[0])
            black++;
        if (answer[1]==guess[1])
            black++;
        if (answer[2]==guess[2])
            black++;
        if (answer[3]==guess[3])
            black++;

        if (answer[1]==guess[0] || answer[2]==guess[0] || answer[3]==guess[0])
            white++;
        if (answer[0]==guess[1] || answer[2]==guess[1] || answer[3]==guess[1])
            white++;
        if (answer[0]==guess[2] || answer[1]==guess[2] || answer[3]==guess[2])
            white++;
        if (answer[0]==guess[3] || answer[1]==guess[3] || answer[2]==guess[3])
            white++;

        if (black==4)
            white=0;

        g2[1][4]=black;
        g2[1][5]=white;

        for (int n = 0;n < 6;n++)
            printf(" %d",g2[1][n]); 

        printf("\n");
    }
    while (answer[0]!=guess[0] || answer[1]!=guess[1] ||
           answer[2]!=guess[2] || answer[3]!=guess[3]);

    printf("BINGO!!!\n");

    return 0;
}

---

Update 2:

for (int slot=0;slot<4;slot++)
{
    if (guess[slot] == answer[slot]) 
        black++;
    else 
        for (int s=0;s<4;s++)
            if (s != slot) 
            {
                if (guess[slot] == answer[s]) 
                    white++;
                break;
            }
}

---

Update 3:

for (int x=0;x<4;x++)
flag[x]=0;

for (int slot = 0;slot < 4;slot++) 
{ 
    if (guess[slot] == answer[slot])  
        if (flag[slot]==1)
            black++; 
    else  
        for (int s=0;s < 4;s++) 
            if (s != slot)  
            { 
                if (guess[slot] == answer[s])
                    if (flag[s]==1)
                    {
                        white++; 
                        break; 
                    }
            } 
} 

---

Update 4

for (int x=0;x<4;x++)
flag[x]=0;

for (int slot = 0;slot < 4;slot++) 
{ 
    if (guess[slot] == answer[slot])  {
        black++; 
        flag[slot]=1;
    }
else  
    for (int s=0;s < 4;s++)
        if (s != slot)
        { 
            if (guess[slot] == answer[s])  
            {
                white++; 
                flag[s]=1;
                break; 
            }
        } 
} 

---

Update 5:

#include "stdafx.h"
#include "stdlib.h" 
#include "time.h"

int _tmain(int argc, _TCHAR* argv[])
{
    int answer[4];
    int guess[4];
    int flag[4];
    int count = 0;

    srand(time(NULL)); 
    /*answer[0] = (rand() % 6)+1;
    answer[1] = (rand() % 6)+1;
    answer[2] = (rand() % 6)+1;
    answer[3] = (rand() % 6)+1;*/

    answer[0] = 1;
    answer[1] = 2;
    answer[2] = 3;
    answer[3] = 4;

    printf("%d %d %d %d\n", answer[0],  answer[1],  answer[2],  answer[3]); 

    do
    {
        int black = 0;
        int white = 0;
        count++;
        printf("Enter 4 numbers, this is your %d guess: ", count);
        scanf("%d %d %d %d", &guess[0], &guess[1], &guess[2], &guess[3]);

        int g2[2][6];

        for (int a = 0;a < 4;a++)
            g2[0][a]=answer[a];

        for (int i = 0;i < 4;i++)
            g2[1][i]=guess[i];

        for (int x=0;x<4;x++)
            flag[x]=0;

        for (int slot = 0;slot < 4;slot++) 
        { 
            if (guess[slot] == answer[slot])  
                black++; 
            else   
                for (int s=0;s < 4;s++)  
                    if (s != slot && guess[slot] == answer[s] && !flag[s]) 
                    {  
                        white++;  
                        flag[s]=1; 
                        break;  
                    }
        } 

        g2[1][4]=black;
        g2[1][5]=white;

        printf("Guess %d: ", count);

        for (int n = 0;n < 4;n++){
            printf(" %d",g2[1][n]);
        }

        printf(" Black: %d White: %d\n", g2[1][4], g2[1][5]);
        printf("\n");
    }
    while (answer[0]!=guess[0] || answer[1]!=guess[1] ||
           answer[2]!=guess[2] || answer[3]!=guess[3]);

    printf("BINGO!!!\n");

    return 0;
}

Answer 1

Suggested alternative (pseudocode):

white = 0;
black = 0;
for slot=0 to 3
  if guess[slot] == answer[slot]
    black++
  else
    for s=0 to 3
      if s != slot
        if guess[slot] == answer[s]
          white++
          break

Update (detail)

 else  
    for (int s=0;s < 4;s++) 
      if (s != slot && guess[slot] == answer[s] && !flag[s])
      { 
          white++; 
          flag[s]=1;
           break; 
      }

I think this should do it: We're checking for another slot that's not the current one, one that's not a perfect (black) match, and that hasn't been used before to flag a black or white.

Answer 2

Knuth answers this in The Computer as Master Mind and acknowledges that it's hard to define it exactly. He suggests this:

1. Make two arrays, ans and guess, with a slot for each color.
2. For each color, populate ans with the number of pegs of that color. Similarly for guess.
3. Add up min(ans[i], guess[i]) for each i. This is whites plus blacks.
4. Add up max(ans[i] - guess[i], 0) for each i. This is the number of whites.

Answer 3

try this:

    for (int x=0;x<4;x++)
        flag[x]=guess[x]==answer[x]?1:0;

    for (int slot = 0;slot < 4;slot++) 
    { 
        if (guess[slot] == answer[slot])  
            black++; 
        else   
            for (int s=0;s < 4;s++)  
                if (!flag[s] && guess[slot] == answer[s]) 
                {  
                    white++;  
                    flag[s]=1; 
                    break;  
                }
    }