title: Replace Upper case letters with Lower case - and vice versa
body: <p>Input String : "This is a String"
  Output " tTHIS IS A sTRING</p>
  
  <p>I'm able to convert the upper case to lower case but somehow I'm not able to link them :(.</p>
  
  <p>here is my code.. could someone please help me out here ?</p>
  
  <pre><code>static void Main()
  {
      string lstr = "";
      string ustr = "";
      Console.WriteLine("Enter the string");
      string str = Console.ReadLine();
  
      char[] strchararr = str.ToCharArray();
  
      for (int i = 0; i &lt; strchararr.Length; i++)
      {
  
          if (strchararr[i]&gt;='a'&amp;&amp; strchararr[i]&lt;='z')
          {
              ustr += char.ToUpper(strchararr[i]);
  
          }
  
          else if (strchararr[i] &gt;= 'A' &amp;&amp; strchararr[i] &lt;= 'Z')
          {
              lstr+=char.ToLower(strchararr[i]);
          }
      }
  }
  </code></pre>