How read read random numbor of strings in c++?

Question

Hello,
As an input, I have a random number of strings (from 10 to 500). Every string is separated from the previous one by "enter". How to read them all and close the program as the user stops adding new strings?
Firstly, I was trying to use

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

int main() {
    string s;
   while (getline(cin, s)) {

    }
    return 0;
}

But in this case, the program never stops and always waiting for new input.

Thank you.

Answer 1

How about this --

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


int main()
{
    string str;
    vector<string> vStrings;
    const size_t min{ 10 }, max{ 20 };

    vStrings.reserve(max);
    cout << "Enter lines, an empty line ends input\n";
    while (getline(cin, str))
    {
        if (str.empty())
        {
            if (vStrings.size() < min)
            {
                cout << "Must enter at least " << min << " lines\n";
                continue;
            }
            break;
        }
        else
        {
            vStrings.emplace_back(move(str));

            if (vStrings.size() == max)
                break;
        }
    }

    cout << "vStrings contains " << vStrings.size() << " strings\n";
    for (auto& s : vStrings)
        cout << s << endl;

    return 0;

}

Answer 2

Hello,
if the user is supposed to enter the random number of strings before the programme exits, do something like this:

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

int main() {
  string s;
  int n;
  cout << "random number n=" <<;
  cin >> n;
  if (n < 20 || n > 500) 
  {
    cout << "wrong n" << endl;
    return 1;
  }

  while (--n > 0 && getline(cin, s))
  {
             // do something with s
  }

  return 0;
}

Regards, Guido

Answer 3

Sorry, I don't know what you mean.

• The while-loop is in one function.
• What do you mean with each symbol as an individual? You use getline, and it will read a string. If you need the characters in the string, use a for loop: for (int i=0; i < s.length(); i++) { c =s[i]; ... }
• The getline will discard the \n at the end of the string. If you want it at the end of the string, then you must add it by yourself, e.g. s += "\n"; char c;
  int n=0;
  while (getline(cin, s))
  {
  n++;
  if (s.length() == 0)
  {
  if (n < 10) ... error routine, or if at least 10 lines needed: continue;
  break; // empty string will break the while loop
  }
  if (n > 500) break; // not more than 500 lines allowed
  // do whatever you want to do with s,
  // e.g. add the \n again
  s += "\n";
  // if you need the single characters in the string, use the for-loop:
  for (int i=0; i<s.length(); i++)
  {
  c = s[i];
  // do whatever you want to do with c
  }
  }