FILE* file = 0;
char filename[25];

printf("Saving grocery list to test.bin...n");

errno_t errorCode = fopen_s(&file, "test.bin", "wb"); //This line is different
//because of MVS...

if (file == NULL )
{
    printf("File could not be opened.n");
    return 0;
}

else
{
    fwrite(&totalGrocery, sizeof(int), totalGrocery, file);
    fwrite(&item, sizeof(struct grocery), totalGrocery, file);
    fclose(file);
    printf("The file has now been saved.n");
}

struct grocery
{
    int id;
    char food[31];
    float quantity;
    char unit[16];
};