Thread: Help needed in cows and bulls

I'm relatively new to c programming and I'm in the learning process.
Using only simple functions, I have written code for the
Cows & Bulls game, otherwise known as mastermind. The program however throws up random values for bulls and cows.Can you please spot the problem and tell me?Forgive me if it's a very basic mistake.

Thanks in advance!

Code:

#include<stdio.h>
#include<conio.h>
#include<math.h>
main()
{
int cows,bulls,i;
char a,b,c,d,A,B,C,D;
clrscr();
printf("Welcome to Mastermind \n\n Player 1,enter the letters of you word.");
a=getchar();b=getchar();c=getchar();d=getchar();
printf("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nPlayer2, please get ready");
for(i=1;i<=10;i++)
    {
     bulls=0;cows=0;
     printf("\nGuess %d\n",i);
     A=getchar();
     B=getchar();
     C=getchar();
     D=getchar();
     if(a==A)bulls=bulls+1;if((a==B)||(a==C)||(a==D))cows+=1;
     if(b==B)bulls=bulls+1;if((b==A)||(b==C)||(b==D))cows+=1;
     if(c==C)bulls=bulls+1;if((c==A)||(c==B)||(c==D))cows+=1;
     if(d==D)bulls=bulls+1;if((d==A)||(d==B)||(d==C))cows+=1;
     if(bulls==4) printf("Congratulations player 2, you have cracked the Mastermind");
     else printf("Bulls = %d Cows = %d",bulls,cows);
     }
getch();
}

This problem gets pretty much everyone.

In short, when asking for input characters are not read straight into your program they instead go into an input buffer and your program reads from that buffer. The newline character ('\n') is stored in this buffer as well.

You need an extra call to getchar to retrieve this newline character.

Haven't actually checked your logic, I just noticed this about the input.

So many people have this problem, thinking that C books don't cover input buffers very well because it's beyond their scope or something?

There's a couple things I think you should do, and it'll help you debug what the actual problem is:

- Lines 20-24 are impossible to read, as you've crammed so much in. At the very least, put each "if" on its own line.
- The statement "bulls = bulls+1" could be replaced with "bulls++" for clarity.
- You're collecting each character individually, instead of doing a fgets() into a char array, and picking out the individual letters.
- Not sure what the extra getch() at the end of the for loop is doing..
- It's bad practice to do main(). The standard is (at the very least) int main().

First of all thanks memcpy & Deadplanet, even if the issue is not resolved yet.
I have done as you suggested.
-I used scanf for accepting variables.
-getch() allows you to compile the program and view the output screen. Otherwise you'll need to press control+F9
& then alt+F5.

Also, I'm using Turbo c if that will help.

Code:

#include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
int cows,bulls,i;
char a,b,c,d,A,B,C,D;
clrscr();
printf("Welcome to Mastermind \n\n Player 1,enter the letters of you word.");
scanf("%c%c%c%c",&a,&b,&c,&d);
printf("Player2, please get ready");
for(i=1;i<=10;i++)
    {
     bulls=0;cows=0;
     printf("\nGuess %d\n",i);
     scanf("%c%c%c%c",&A,&B,&C,&D);
     if(a==A)bulls++;
     if((a==B)||(a==C)||(a==D))cows++;
     if(b==B)bulls++;
                   if((b==A)||(b==C)||(b==D))cows++;
     if(c==C)bulls++;
                   if((c==A)||(c==B)||(c==D))cows++;
     if(d==D)bulls++;
                   if((d==A)||(d==B)||(d==C))cows++;
     if(bulls==4) printf("Congratulations player 2, you have cracked the Mastermind");
     else printf("Bulls = %d Cows = %d",bulls,cows);
     }
getch();
}



You need to make sure that the newline has been read after the 4 letters of the word. A cheap (non-robust) solution would be to add another getchar (which you should be using instead of scanf) after reading the word, which of course only works if the newline is directly after the 4 letters (and there's no spaces before the letters).

A better solution would be to write a function to read the word, skipping initial spaces, and consuming any extra characters including the newline after the 4 characters that you want.

Also, your for loop with index d should go from 0 to 3, not 1 to 4, since array indices start at 0.

Even with these fixes it looks like your algorithm still won't work correctly, but that's another story.

I don't know if you terribly attached to scanf() but if I were you I'd probably be using fgets();

Like this:

Code:

//at top
char guess[5];

//to get input
fgets(guess, sizeof(guess), stdin);

It's totally up to you though, I just dislike scanf() alot.

@Nikolas, as you can see, someone has attempted to do your homework for you. If I was you, I would complain ... the more indignant, the better.

At any rate, the proffered code is incorrect.

@oogabooga Explain