Check value of all cells in datagridview for null in c#
<p>i want to check and set the value of all those cells in datagridview which have null values
like </p>

<pre><code>firstname          lastname     DOB
AAA                             12/12/1212
BB                  CC
                    DD          12/12/1212
</code></pre>

<p>now output should be </p>

<pre><code> firstname          lastname     DOB
    AAA                null      12/12/1212
    BB                  CC       null
    null                DD       12/12/1212
</code></pre>
