title: How to convert the string of integer to 2D vector of integers?
body: <p>Given my desired output to be a square output (don't need any spaces between them):</p>
  
  <pre><code>1234
  2345
  3456
  4567
  </code></pre>
  
  <p>Given the same square of numbers, but each one of them being a <code>std::string</code>, how can I implement a <em>2D vector</em> that will take <em>each character</em> of the square and first convert each character into an <code>int</code> and then store into a <em>2D vector of rows and column</em> to make the exact same square?</p>
  
  <p>I know that a 2D vector needs to be </p>
  
  <pre><code>vector&lt;vector&lt;int&gt;&gt; square_vector;
  </code></pre>
  
  <p>But I was having trouble taking all of the paired rows and column.</p>
  
  <p>EDIT:
  If my square is </p>
  
  <pre><code>1234
  2345
  3456
  4567
  </code></pre>
  
  <p>I want to go through the first row <code>1234</code> first. Then within that row, I want to go through each column character <code>1, 2, 3, 4</code> and convert each character to an <code>int</code>. After converting, I want to <code>push_back</code> as a row into the 2D vector. After a row is complete, I would like to move on to the next row and perform the same task.</p>