0

I'm currently working on a function that takes user input to select a point on a Battleship game board. The rows are represented with the letters A-J while the columns are represented by numbers 0-9. I want the user to be able to type in something like "B5" and then take each component into a separate variable (so B would be stored into a char variable and 5 into an int variable). How can I do this in C?

spookikitti
  • 1
  • 1
  • 2
    Please show what you have tried, but my crystal ball says: [scanf() leaves the newline char in the buffer](https://stackoverflow.com/questions/5240789/scanf-leaves-the-new-line-char-in-the-buffer). – Weather Vane Oct 24 '22 at 18:24
  • The best way to do this depends on how tolerant you want to be of user typing mistakes. – stark Oct 24 '22 at 18:26
  • A good way might be to enter a string with `fgets` and examine the first character and subsequent integer for validity. Then use `fgets` for every other input, whatever its purpose. – Weather Vane Oct 24 '22 at 18:29
  • https://ericlippert.com/2014/03/21/find-a-simpler-problem/ I.e. first do a program which can take a single non-digit character as input. Then write a program that can take a single digit character as input and turn it into an `int` < 10. Then try to combine them. that will probably help you to focus your question on a more specific programming problem and allow you to give an [mre], or two, here. – Yunnosch Oct 24 '22 at 18:42
  • Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. – Community Oct 25 '22 at 03:15

1 Answers1

0

There are probably a lot of ways to approach this, but the following code snippet offers up a proof-of-principle example using the entry of the coordinates as a string and then evaluating the two alphanumeric characters entered.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int check_coordinate(char * xy)
{
    if (xy[0] < 'A' || xy[0] > 'J')
    {
        return 0;
    }

    if (xy[1] < '0' || xy[1] > '9')
    {
        return 0;
    }

    printf("The first portion of the coordinate is: %c, the second portion of the coordinate is: %c\n", xy[0], xy[1]);

    return 1;
}

int fire(char * xy)
{
    /* Function to see if there was a hit or a miss */

    return 0;
}

int main()
{
    char xy[4];
    int result = 0;

    while (1)
    {
        printf("Enter coordinate to fire upon: ");
        scanf("%s", xy);
        if (strcmp(xy, "End") == 0)
        {
            break;
        }

        if (check_coordinate(xy) == 0)
        {
            printf("An invalid coordinate was entered - try again\n");
        }
        else
        {
            result = fire(xy);
        }
    }

    return 0;
}

Here is some sample output noting when an invalid coordinate was entered as opposed to a valid coordinate.

@Dev:~/C_Programs/Console/Battleship/bin/Release$ ./Battleship 
Enter coordinate to fire upon: C8
The first portion of the coordinate is: C, the second portion of the coordinate is: 8
Enter coordinate to fire upon: K7
An invalid coordinate was entered - try again
Enter coordinate to fire upon: D4
The first portion of the coordinate is: D, the second portion of the coordinate is: 4
Enter coordinate to fire upon: End

Ultimately, you might come up with a different approach to checking coordinates, but this should give you some food for thought.

NoDakker
  • 3,390
  • 1
  • 10
  • 11