count_if(): A unary predicate that determines if number is divisible by 3 : count_if « STL Algorithms Non modifying sequence operations « C++ Tutorial

1. C++ Tutorial
2. STL Algorithms Non modifying sequence operations
3. count_if

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
   

bool dividesBy3(int i)
{
  if((i%3) == 0) return true;
   
  return false;
}
   
int main()
{
  vector<int> v;
  int i;
   
  for(i=1; i < 20; i++) v.push_back(i);
   
  for(i=0; i<v.size(); i++)
    cout << v[i] << endl;
   
  i = count_if(v.begin(), v.end(), dividesBy3);
  cout << i << " numbers are divisible by 3.\n";
   
  return 0;
}