将文本文件读入2D数组

Question

So currently I have a working code that is able to read in a text file that contains a 9x9 board each slot in the 2D array is a number between 1-9; however, some slots have a '-' character mixed into them randomly. The only way I found that I could read all the lines successfully and then print them was using a char sudoku[9][9] but this greatly affects other parts of my current assignment.

The file should just be 9 consecutive rows like so:

123-56-89
4561-3--9

etc...

Could someone show me a way I could successfully scan in the text file contents into a INTEGER 2D array instead of a char one?

int main(){
 int i, j;
 char sudoku[9][9];
    char filename[100];

        printf("Please enter file name (W/O .txt): ");
        scanf("%s", filename);

        FILE *file1 = fopen(filename, "r");

        for(i=0;i<9;i++){
            for(j=0;j<9;j++){
                fscanf(file1,"%c\t", &sudoku[i][j]);
            }
        }

        for(i=0;i<9;i++){
            for(j=0;j<9;j++){
                printf("%2c", sudoku[i][j]);
                }
            printf("\n");
        }

fclose(file1);
}

Answer 1

int suduku[9][9];

for (int i = 0; i < 9; i++)
{
    for (int j = 0; j < 9; j++)
    {
        char c;
        if (fscanf(file1, " %c", &c) != 1)
            …report read failure and exit…
        else if (isdigit((unsigned char)c))
            sudoku[i][j] = c - '0';
        else
            sudoku[i][j] = 0;
    }
}

Read the character into a character, then convert to an appropriate integer. Note that the code won't care if each character from the matrix is separated from the next by a dozen blank lines and there are 20 spaces before the character, or if the whole input is 81 characters on a single line, or any other variation. As long as there are at least 81 non-white space characters in the file, it'll be OK.

Answer 2

#include <stdlib.h>
/* ... */
int sudoku[9][9];
/* ... */
for(i = 0; i < 9; i++) {
    for(j = 0; j < 9; j++) {
        char s[] = "0";
        fscanf(file1, " %c", &s[0]);
        sudoku[i][j] = atoi(s);
    }
}

I prefer to call a standard library function where possible to perform the integer conversion. Here, I'm using atoi(). If it sees a digit, it will return its integer value. If is sees anything else, including the '-' character, it will return 0. If fscanf() runs out of characters, atoi() will also return 0 (since we are initializing s to "0" in every iteration), effectively padding out the rest of the array with '-' characters. (Notice that s is technically a string rather than a character, since that is what atoi() expects as input, but fscanf() will only overwrite its first byte where the character is stored.)