In gridview have to find out maximum length in column

Friends,

I am working on excel sheet. i populated gridview with excel sheet data.
the gridview has one column.
have to find out the maximum length of String in that column.
For example:
gridviews has one column with three names
Ram
Murali
Hari Krishna Murthy Sharma

and it has to show that Hari Krishna Murthy Sharma occupies maximum length of characters.

Code needed.
Thanks in Advance.

Regards,
Ramu