csh: how to test for blank correctly?

Question

I want to test if a variable is totally empty in csh.

set R='dddd aaa'
if ( '${R}' ) then
    echo not empty

else
    echo 1111
endif

However it apparently does not work.

It gives this error message:

/usr/bin/test: argument expected
if: Expression Syntax.

Answer 1

Use

if ( "x$R" == "x" ) then
    echo empty
else
    echo not empty
endif

The C shell doesn't have an empty operator like bash. Also, you can't quote with ' as it will prevent the variable expansion.