C語言按行讀取文件/寫數組到文件

#include <cstdio>
#include <cstdlib>
int main()
{
    int row, col;
    FILE *fp = fopen("In.txt", "r");
    FILE *fd = fopen("Out.txt", "w");
    if (!fp || !fd)
    {
        printf("File doesn't exist\n");
        exit(0);
    }

    fscanf(fp, "%d %d", &row, &col);
    int Data[row][col];
    for (int i = 0; i < row; i++)
    {
        for (int j = 0; j < col; j++)
        {
            fscanf(fp, "%d", &Data[i][j]);
        }
    }
    for (int i = 0; i < row; i++)
    {
        for (int j = 0; j < col; j++)
        {
            fprintf(fd, "%d ", Data[i][j] * Data[i][j]);
            printf("%d ", Data[i][j]);
        }
        printf("\n");
        fprintf(fd, "\n");
    }
    fclose(fp);
    fclose(fd);
    return 0;
}