If statement

[C# Programming]

Hello,

I have couple of question about if statement.

When I create password verifying program,

at least 8 characters long is
if (password.Length < 8)
valid = false;

like this, right?

Then, how can I make program that must contain at least one digit and one uppercase for the password.

Then, I tried to create
while (valid && i < 1)
{
if (!Char.IsLetter(custID[i]))
valid = false;
i++;
}
like this, but it's not working.

Please tell me.