Question

I have written a code that reads from a file named network.dat

The code I wrote is

    f = fopen("network.dat", "r");
    if(f == NULL)
        exit(1);
    int read, N;

    printf("%p\n", f);//output file pointer, included this just to check if file is opened properly
    fscanf(f, "%d%d", &N, &read);//error here
    cout<<N; 

The file is being opened correctly and am getting the file pointer (49897488) as output but the line following it is where program stops working and I don’t get N as output.
Please tell if other detail is required.
Contents of network.dat are

10 1
1   6   1.28646
1   7   1.2585
2   9   1.33856

and so on. Am just focusing on first 2 numbers from the file i.e. 10 and 1.

Answer 1

As I stated in my comment, the problem is that your format specifier is incorrect. Try

fscanf(f, "%d%d", &N, &read);

Since you’re using cout I’m fathoming a guess that this is actually C++ code… honestly, you should really not be doing this the canonical C way. Instead, use ifstream.

std::ifstream input("network.dat");
int N, read;
input >> N >> read;
std::cout << N << ' ' << read << std::endl;