How to extract the numbers in a file in C++?

Question

I have some similar files like this: 15 12 0 0 168 0 2 92 (more numbers)...

I want to extract the first two (in this case: 15 and 12) into integers, how can I accomplish that? By the way, the first two numbers sometime will be unit digits sometimes will be hundreds digits.

Answer 1

Regardless of the language, this will typically consist of the following steps:

1. Open the file
2. Read (formatted) the first two integers
3. Close the file

In C++, we can use ifstream

1. To open:

std::ifstream fil;
fil.open("in.txt");

2. To read:

int x, y;
fil >> x >> y;

3. To close:

fil.close();

Make sure to include the fstream header:

#include <fstream>