title: How do I get the intersection between two arrays as a new array?
body: <p>I faced this problem many times during various situations. It is generic to all programming languages although I am comfortable with C or Java.</p>
  
  <p>Let us consider two arrays (or collections):</p>
  
  <pre><code>char[] A = {'a', 'b', 'c', 'd'};
  char[] B = {'c', 'd', 'e', 'f'};
  </code></pre>
  
  <p>How do I get the common elements between the two arrays as a new array?
  In this case, the intersection of array A and B is <code>char[] c = {'c', 'd'}</code>.</p>
  
  <p>I want to avoid the repeated iteration of one array inside the other array which will
  increase the execution time by (length of A times length of B) which is too much in the case of huge arrays.</p>
  
  <p>Is there any way we could do a single pass in each array to get the common elements?</p>