Помогите написать код C++ со строками

#include <algorithm>
#include <iostream>
#include <string>
#include <regex>
#include <vector>
using namespace std;
vector<string> words(const string& str, const string& signs) {
const regex re{ signs };
const sregex_token_iterator iter{ str.begin(), str.end(), re, -1 };
return { iter, {} };
}
int main() {
system("chcp 1251 > nul");
cout << "Исходная строка: ";
string line;
getline(cin, line);
const string re(R"([ ]+)");
auto box = words(line, re);
const auto target = [](string s) { return ~s.length() & 1; };
box.erase(remove_if(box.begin(), box.end(), target), box.end());
box.shrink_to_fit();
line.clear();
for (const auto& x : box) line += x + ' ';
line.pop_back();
cout << "Новая строка: " << line;
system("pause > nul");
}

#include <iostream>

using namespace std;

int main()
{
const char AZ[] = "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz";
const int size = 1000;
char * S, * S2;
S = new char [size];
S2 = new char [size];
int i = 0;
char c;
while( (c = getchar()) != '\n' && i < (size - 1) )
{
S[i] = c;
i++;
}
S[i] = '\0';

int j = 0;
int count = 0;
for(int x = 0; x < i; x++)
{
bool is_b = false;
for(int y = 0; y < 52; y++)
if(S[x] == AZ[y])
{
is_b = true;
break;
}
if(is_b)
{
count++;
}
else
{
if(count > 0)
{
if(count % 2 == 1)
{
for(int z = x - count; z < x; z++)
{
S2[j] = S[z];
j++;
}
S2[j] = S[x];
j++;
}
else
{
S2[j] = S[x];
j++;
}
count = 0;
}
else
{
S2[j] = S[x];
j++;
}
}
}
S2[j] = '\0';

cout << S2 << endl;
delete [] S2;
S2 = (char *) nullptr;
delete [] S;
S = (char *) nullptr;

return 0;
}