prime number c++

prime.cpp

#include <iostream>
#include <vector>
#include <time.h>
#include <float.h>
#include <math.h>

using namespace std;

//int checkPrime(int num, vector<int> array);
int checkPrime(int num, vector<int> &array);
int main(){
  clock_t start = clock();
  cout << 2 << endl;
  cout << 3 << endl;
  int num = 5;
  vector<int> array;
  array.push_back(2);
  array.push_back(3);
  int i = 1;
  while(i < 100000){
    int checkedNum;
    checkedNum = checkPrime(num, array);
    if(checkedNum != 0){
      cout << checkedNum << endl;
    }
    num += 2;
    i++;
  }
  clock_t stop = clock();
  cout << (double)(stop - start) / CLOCKS_PER_SEC * 1000 <<  "ミリ秒" << endl;
}

//int checkPrime(int num, vector<int> array){
int checkPrime(int num, vector<int> &array){
  for(int i =0; i < array.size(); i++){
    if((num % array[i]) == 0){
      return 0;
    }
    if((double)array[i] > sqrt((double)num)){
      break;
    }
  }
  array.push_back(num);
  return num; 
}