Find all a substring's occurrences and locations

Question

I\'m writing a program to parse some data saved as text files. What I am trying to do is find the location of every needle in a haystack. I already can read the file in and

Answer 1

I know an answer has been accepted, but this will also work, and will save you having to load in the file to a string..

#include 
#include 
#include 
#include 

using namespace std;

int main(void)
{
  const char foo[] = "foo";
  const size_t s_len = sizeof(foo) - 1; // ignore \0
  char block[s_len] = {0};

  ifstream f_in();

  vector f_pos;

  while(f_in.good())
  {
    fill(block, block + s_len, 0); // pedantic I guess..
    size_t cpos = f_in.tellg();
    // Get block by block..
    f_in.read(block, s_len);
    if (equal(block, block + s_len, foo))
    {
      f_pos.push_back(cpos);
    }
    else
    {
      f_in.seekg(cpos + 1); // rewind
    }
  }
}