Prime number + strings

#include <iostream>
#include <string>
#include <cstdlib>

using namespace std;

    string ns;

strRemove(string s)
{
    for(int i =0; i<s.length(); i++){
            if(s.at(i)!=' ')
            {
                ns+=s.at(i);
            }

    }

}


stringSpace(string inputString, int spaceNumber)
{
   int found = -1;
   int lookedSpace = 0;
   int counter = 0;
   do
   {
       found = inputString.find(" ", found+1);
       if(found!=-1)
       {
           lookedSpace = found;
           counter++;
       }
   }
  // while(found<=words.length()-15);
      while(counter<spaceNumber);
      return lookedSpace;

}
primeNumberCheck(int n) {

int i, m=0, flag=0;
  //cout << "Enter the Number to check Prime: ";
 // cin >> n;
  m=n/2;
  for(i = 2; i <= m; i++)
  {
      if(n % i == 0)
      {
          cout<<"Number is not Prime."<<endl;
          flag=1;
          break;
      }
  }
  if (flag==0)
      cout << "Number is Prime."<<endl;
  return 0;
}

 int main()
{

   string words = "one two three four five six";
   string word = "zero";
  /* int found = -1;
   int lastSpace = 0;
   int counter = 0;
   do
   {
       found = words.find(" ", found+1);
       if(found!=-1)
       {
           lastSpace = found;
           counter++;
       }
   }
  // while(found<=words.length()-15);
      while(counter<2);
    */
   //words = words.substr(0,found) + " "+ word +words.substr(found);

   //words = words.substr(0,lastSpace) + " "+ word +words.substr(lastSpace);
   primeNumberCheck(10);
   int spaceFound = stringSpace(words,1);
  // int spaceFound1 = stringSpace(words,1);
   //int spaceFound2 = stringSpace(words,3);
   words = words.substr(0,spaceFound);
   strRemove(words);
   string outputString = ns; // The string from STR REMOVE
    //words = words.substr(spaceFound1,spaceFound2);
   cout << outputString;
    return 0;
}