Question

How do I set up my read function?

12 Read Sudoku board from a file Implement a function with the following prototype: int read_sudoku_board (const char file_name[], int board[9][9]); This function should read a Sudoku board from a file, in the format described in Step 13. Ignore any characters after the 9th line in the file. The function should return 0 on success, -1 if any file I/O error occurred, -2 if an invalid character (other than 1-9 and -) was encountered and -3 if the file format is invalid (e.g. not enough lines or lines too short) 13 Save Sudoku board to a file Implement a function with the following prototype: int write_sudoku_board(const char file_name[], int board[91[91); This function should save the board to a file. The function should return 0 on success, -1 if any file I/O error occurred and -2 if an invalid board was provided. In the output file, write a line for each row, with no spaces, and use a dash (the '- ' character) to represent blanks. For example, the Sudoku board on page 1 should be saved as follows: 6-32-8-5 4--1 7 23---7-6 4--1 57--492 3---64 7 1 31-758-6 Hint: If you have read the board from the same file (using the function from Step 12), make sure you close the file and re-open it before saving the board

here's my code so far:

int read_sudoku_board(const char file_name[], int board[9][9])
{
    FILE * fp = fopen("sudoku.txt", "r");
    int a,i,j,c;
    int count = 0;
    for(i = 0; i < a; i++){

        for(j = 0;j < 9;j++){
            c = fgetc(fp);
            if(c == '-'){
                board[i][j] = 0;
            }
            else if(c >= 1 && c <= 9)
                printf(" %d");
            else
                return -2;

        }
        count++;

    }
    if(count != a-1)
        return -1;
    else
        return 0;


}

Answer 1

Please find the program to read and write the board values:

Program:

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

#define SIZE 10
#define ROW 9
#define COL 9
int board[9][9];

int read_sudoku_board(const char filename[], int board[ROW][COL])
{
FILE *fp = fopen(filename, "r");
int count = 0, i=0;
char row[SIZE]={'\0'};
int j=0, k=0;

char outfile[50] = {'\0'};

strncat(outfile, filename, strlen(filename));
strncat(outfile, ".out", strlen(".out"));

if(fp == NULL)
{
printf("Error opening file\n");
return -1;
}

memset(row, '\0', sizeof(row));
while( fscanf(fp, "%s\n"
,&row) != EOF )
{
if(j > 8)
break;

if(strlen(row) != 9)
{
printf("Error not enough lines or short\n");
return -3;
}

for(i=0; i<strlen(row); i++)
{
if((row[i] >= 49 && row[i] <= 58) || (row[i] == '-'))
{
if(row[i] == '-')
board[j][k++] = 0;
else
board[j][k++] = row[i] - '0';
}
else
{
printf("Error Invalid Chars\n");
return -2;
}
}
j++;
k=0;
}

fclose(fp);

write_sudoku_board(outfile, board);
}

int write_sudoku_board(const char filename[], int board[ROW][COL])
{
int i=0, j=0;
FILE *fp=fopen(filename, "w");

if(fp == NULL)
{
printf("Error opening file\n");
return -1;
}

for(i=0; i<ROW; i++)
{
for(j=0; j<COL; j++)
{
if(board[i][j])
fprintf(fp, "%d", board[i][j]);
else
fprintf(fp, "-");
}
fprintf(fp, "\n");
}

printf("Successfully created the output file %s with board values\n", filename);
fclose(fp);
}
int main( int argc, char *argv[])
{

if (argc != 2)
{
printf("Usage: %s <file-name>\n", argv[0]);
return -1;
}

read_sudoku_board(argv[1], board);

return -3;
}

Output:

USER> cat data.txt

1-3-5-7-1
1-3-5-7-9
2-3-5-7-9
--3-5-7-9
1-3-5-7-9
1-3-5-7-9
--------9
1-3-5-7-9
1-3-5-7-9

USER > ./a.out data.txt
Successfully created the output file data.txt.out with board values

USER > cat data.txt.out

1-3-5-7-1
1-3-5-7-9
2-3-5-7-9
--3-5-7-9
1-3-5-7-9
1-3-5-7-9
--------9
1-3-5-7-9
1-3-5-7-9

USER >./a.out
Usage: ./a.out <file-name>