RE: st: RE: Making a local with no assigned value zero

["Nick Cox" <n.j.cox@durham.ac.uk>]

But I didn't recommend that at all. Please read my post again. 

You must write "`y1'" and test whether it differs from the empty string "". 

I could explain more, but it is more important that you read up the basics of macros in [U] because otherwise you are not going to make any progress here. 

Nick 
n.j.cox@durham.ac.uk 

George Chioran

Thank you for the reply. However I do not seem to manage to make the `y1 ' variable equal to nothing. When I type: 
if `y1' == "" { 
local y1 = 0
 }
I get an error saying type mismatch, and I assume it is because the " " symbol is maybe not recognized as no value? Did I type it in wrong, or would there be another way of saying that `y1' is equal to nothing? Do you also know how I can delete/drop locals once I create them? 

From: Nick Cox <n.j.cox@durham.ac.uk>

There are various fixes. Here are some: 

1. 

if "`y1'" == "" local y1 = 0 
local x1 = `x1' + `y1' 

2. 

local x1 = cond("`y1'" != "", `x1' + `y1', `x1') 

3. 

if "`y1'" != "" local x1 = `x1' + `y1' 

Nick 
n.j.cox@durham.ac.uk 

George Chioran

My code goes like
this: local x1 = `x1’ + `y1’. I get the `y1’ variable through repeated loops
and sometimes `y1’ is not assigned any value. 
When `y1’ does not
have any value, the line local x1 = `x1’ + `y1’ stops my program and I get an invalid
syntax error. 

My question is: Could
I somehow make the local `y1’ to be equal to zero, or not to be taken into
consideration in my sum in case `y1’ is not assigned any value? 


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