Missing operand error.

[mudassi...@gmail.com]

Hello everyone. Can someone please help me with this error.

Terminal shows MISSING OPERAND in "set payload [expr - $val(payload)]"... Am stuck here. Help required please..

[Christian Gollwitzer]

Am 03.02.14 07:30, schrieb mudassi...@gmail.com:

> Hello everyone. Can someone please help me with this error.
>
> Terminal shows MISSING OPERAND in "set payload [expr - $val(payload)]"... Am stuck here. Help required please..
>

1. You should brace your expressions:

set payload [expr {- $val(payload)}]

2. Probably val(payload) is an empty string?

(Tests) 51 % set val(payload) ""
(Tests) 52 % set payload [expr - $val(payload)]
missing operand at _@_
in expression "- _@_"

(Tests) 53 % set payload [expr {- $val(payload)}]
can't use empty string as operand of "-"


Christian

[Rich]

mudassi...@gmail.com wrote:
: Hello everyone. Can someone please help me with this error.

: Terminal shows MISSING OPERAND in "set payload [expr - $val(payload)]"...

missing operand---^

You need to write "expr $a - $b"

Or, better yet, "expr {$a - $b}"

[Uwe Klein]

"-" being a dual arg operator was my first thought too.

But .. wrong.

% set tcl_patchLevel
8.6.0

% expr - 4711
-4711

% expr { - 4711 }
-4711

% set myvalue ""

% expr - $myvalue

missing operand at _@_
in expression "- _@_"

% expr { - $myvalue }

can't use empty string as operand of "-"

i.e. this prooves
that the OP has assigned "" to val(payload)

uwe

[Arjen Markus]

On Monday, February 3, 2014 1:09:51 PM UTC+1, Uwe Klein wrote:

>
> i.e. this prooves
>
> that the OP has assigned "" to val(payload)
>

Not necessarily. You get a similar with:

expr - 1 2

(and variants). The actual error message is more informative than just "missing operand" though. If OP can show us the entire message, we may be of even more help.

Regards,

Arjen

[Uwe Klein]

When did this _@_ error indicator make it into the expr machine ?

% set myvalue "1 2"
1 2
% expr - $myvalue
missing operator at _@_
in expression "- 1 _@_2"
% expr { - $myvalue }
can't use non-numeric string as operand of "-"
%


uwe

[bsall...@yahoo.com]

If you want an negative value
(-1)*5