How to draw x=2 in ROOT?

[meixue]

I want to draw a line like x=2 using TLine, but it always report an error like this:

I have tried different type like int; float ,and double, but it still say it is the wrong type. Do you know where is the problem？

I have defined x1,x2,y1,y2 as different type.

[Wile_E_Coyote]

TLine *l1 = new TLine(x1, y1, x2, y2);

[meixue]

I missed that. Thank you !