C++ ::  String Termination Using The Getline Function?

I came across a strange problem while writing a program using the getline function. I understand that when using the getline function an input string will terminate when the "enter" key is pressed and in the following program it works as one would suspect.

#include <iostream>
#include <string>
using namespace std;
int main() {
string str;
cout << "Enter: ";
getline(cin, str);
cout << str;
}

However when I use it in this next program (below) that I have been working on it will only terminate after pressing the "enter" key if the first character is a number, otherwise it will not terminate. So the question is: How do I get it to terminate the string regardless of the input order?

#include <iostream>
#include <string>
using namespace std;
int i = 0, j;
int numValue;

[code]....

Additional Info: the purpose of this program is to change a character, which is extracted from a string, into an equivalent numerical value, if the character is an integer, and assign it to an int variable. I plan on eventually adapting it to return the correct value of a multi-character integer such as 123.