Строки в С++

#include "stdafx.h"
#include <iostream>
#include <cstring>
using namespace std;
void main()
{
char s[255];
cout<<"Tekst: ";
gets(s);
unsigned int k,i;
k=0;
for (i=0;s[i]!='\0';i++)
 if ((s[i]==' ')&&(s[i+1]!=' '))
 k+=1;
if (s[0]!=' ')
    k=k+1;
cout<<"kol=: "<<k<<endl;
system("pause");
}

#include <sstream>
#include <iterator>
#include <algorithm>
#include <string>
#include <iostream>
using namespace std;
int main()
{
    string line;
    getline(cin, line);
    copy_if(istream_iterator<string>(istringstream(line)), istream_iterator<string>(), ostream_iterator<string>(cout, "\n"), [](const string& word) {return word.find('a') != string::npos; });
}

#include <iostream>
#include <string>
#include <sstream>
#include<vector>
 
using namespace std;
void find_words_with_symbol(string &txt, char ch, vector<string> &words)
{
stringstream ss(txt);
string word;
while(ss>>word)
if(word.find(ch)!=string::npos)words.push_back(word); 
} 
int main(int argc, char* argv[])
{
string txt_str;
cout<<"Input the text ";
getline(cin, txt_str);
char ch;
cout<<"Input the containing symbol ";
cin>>ch;
vector<string> words;
find_words_with_symbol(txt_str, ch, words);
vector<string>::iterator it=words.begin(), it_end=words.end();
cout<<words.size()<<endl;
for( ; it!=it_end; ++it)cout<<*(it)<<endl;
system("pause");
  return 0;
}