.. highlight:: c++
  :linenothreshold: 5

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Using getline after extraction
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The Problem
===========
When using the ``getline`` function to read in text all the way to the
delimiter (default to the new line character), the text may be empty after the
read if the delimiter is the first character in the string. It causes the
problem that if you call this function after an extraction ``>>`` operation,
you may potentially read in an empty string.

The Solution
============
+ Option 1: keep calling getline until you get a non-empty read
+ Option 2: clean up after inputs with leftovers such as extraction operations
+ A formal way: make a function to do the work

Code Example
============

::

  // ==== Wrong ====
  int input;
  string line;

  cout << "Input an int: ";
  cin >> input;  // leaves a new line character as the first char in the stream
  cout << "Input a line of text (may contain spaces): ";
  getline(cin, line);  // the line variable will be an empty string

  // ==== Correct ====
  // option 1: protect the getline and replace the getline with:
  do {
    getline(cin, line);
  } while (line.empty());

  // option 2: protect the extraction add after the last >> before getline
  // to clear the leftover
  cin.ignore();
  cin.ignore(numeric_limits<streamsize>::max(), '\n'); // a safer version

  // recommended: make a function
  string readline() {
    string text;
    // text is initially empty so a while loop works here
    while (text.empty()) getline(cin, line);
    return text;
  }
  // to call:
  line = readline();