Displaying a vector of strings in C++

Question

I'm sorry if this is a repeat question but I already tried to search for an answer and came up empty handed. So basically I just want to add strings (single words) to the back of a vector and then display the stored strings as a single string. I am quite the rookie.

#include <iostream>
#include <vector>
#include <string>
#include <cctype>
using namespace std;


int main(int a, char* b [])
{
    vector<string> userString;      
    string word;        
    string sentence = "";           
    for (decltype(userString.size()) i = 0; i <= userString.size() - 1; i++)
    {
        cin >> word;
        userString.push_back(word);
        sentence += userString[i] + " ";
    }
    cout << sentence;
    system("PAUSE");
    return 0;
}

Why doesn't this work?

EDIT

int main(int a, char* b [])
{
    cout << "Enter a sequence of words. Enter '.' \n";
    vector<string> userString;      
    string word;                    
    string sentence = "";           /
    int wordCount = 0;
    while (getline(cin, word))
    {
        if (word == ".")
        {
            break;
        }
        userString.push_back(word);
    }
    for (decltype(userString.size()) i = 0; i <= userString.size() - 1; i++)
    {
        sentence += userString[i] + " ";
        wordCount += 1;
        if (wordCount == 8)
        {
            sentence = sentence + "\n";
                    wordCount = 0;
        }
    }
    cout << sentence << endl; 
    system("PAUSE");
    return 0;
}

So my new program works. It just puts values at the back of a vector and prints them out 8 words to a line. I know there's easier ways but I'm just learning vectors and I'm going in baby steps. Thanks for the help guys.

Answer 1

Because userString is empty. You only declare it

vector<string> userString;     

but never add anything, so the for loop won't even run.