Reading in a file to create multiple "minesweeper"ish arrays - c

Question

What I got so far, is a .in file that will create 100 arrays, followed by how many "mines" are on the board, and then 2 numbers for each "mine" representing where they will be placed on the array. This is for my beginner C class, and honestly we've not been taught properly for something this advanced (i say advanced using the term lightly). I know how to read in files, and I know how to create an array, but im unsure how I would read in that many lines, switching from mines to placement over and over again. I also find myself confused as to how to change an array number from 0 to another number based on where a mine is placed.
An example input file:
1
4
1 3
7 5
7 3
3 3
Where the 1 in the first line means we have one board. The 4 on the next line means it will have 4 bombs. The following 4 lines describe the position of the bomb in the array as row column.
Is there anything that anyone can offer me to point me in the right direction?

Answer 1

Below is a partial solution, it leaves a few parts as an exercise for the OP.
#include <stdio.h>
#include <stdlib.h>
#define BOARD_SIZE 8
int main(void) {
FILE *fp;
fp = fopen("mines.in","r");
if ( fp == NULL ) {
fprintf(stderr,"Could not open file\n");
return 1;
}
int nBoards = 0;
int nMines = 0;
int col;
int row;
int currentBoard = 0;
/* We know the first row is going to be the number of boards */
fscanf(fp,"%d",&nBoards);
printf("We have %d boards\n",nBoards);
while ( fscanf(fp,"%d",&nMines) > 0 ) {
int i,j;
/* initialize board as all zeros */
int board[BOARD_SIZE][BOARD_SIZE] = { {0} };
currentBoard++;
printf("Board %d:\n",currentBoard);
/* Read in and set the mines */
for (i=0; i<nMines; i++) {
fscanf(fp,"%d %d",&col,&row);
board[col-1][row-1] = 9;
}
/* Add mine proximity */
for (i=0; i<BOARD_SIZE; i++) {
for (j=0; j<BOARD_SIZE; j++) {
if ( board[i][j] == 9 ) { /* we have a mine */
/* Square to the left */
if (j > 0 && board[i][j-1] != 9) {
board[i][j-1]++;
}
/* Square to the right */
/* Left as exercise for the OP*/
/* Square above */
/* Left as exercise for the OP*/
/* Square below */
/* Left as exercise for the OP*/
}
}
/* Print out the board */
for (i=0; i<BOARD_SIZE; i++) {
for (j=0; j<BOARD_SIZE; j++) {
printf("%d ",board[i][j]);
}
printf("\n");
}
printf("\n");
}
fclose(fp);
if (currentBoard != nBoards) {
fprintf(stderr,"Expected %d boards, read in %d boards\n",nBoards,currentBoard);
return 1;
}
return 0;
}
The code reads in the first line to record the number of boards, then it loops over the blocks of data containing the number of mines and the mine locations. The while loop will perform an fscanf on the lines containing the number of mines, and in the body of the while loop the different mine locations will be read in to the number defined for the board.
Once we have all the mine locations we can calculate the numbers in other squares on the board, only one of which I've shown in the code (others are similar).
Note that the above code does almost no error handling and almost no validation on the input file - if the input file is wrong you could get errors i.e. 'out of range' accesses to arrays. I've left out such checks to make the underlying logic of the program clearer.
Note also that I've assumed that the input indexs are '1'-indexed (i.e. in the range [1,8] rather than '0'-indexed as C expects (i.e. in the range [0,7]), hence the substitution of 1 in the line board[col-1][row-1] = 9;.