String value should be converted into Capital letters

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C#

ASP.NET

C#4.0

Hi,


I have a small doubt , in my page i have a string datatype value . whatever i pass the string value that should be converted into capital letter .How to do this

for ex:

string x="Null";
string x="nUll";
string x="NUll";
string x="NULL";
.........
.........

these are my sample values , whatever i pass i want to be convert that value into capital letters only how to do this.

final result:

NULL

can anyone help me...

Thanks in Advance....