Contradiction of variable existence
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Hello,
I met following situation. In workspace exist some string variable strF. I need to verify its existence and if it is not present, I should perform some actions. But I have following contradiction:
~exist(strF,"var") gives me logical 1, which means that strF don't exist. This is not correct.
But if I run command
exist strF
I have 1, that means that this variable exist. But when I try to realize this infomation by something like
TT = exist(strF) gives me 0!
How correctly determine existence of this variable?
6 comentarios
Voss
el 15 de Feb. de 2024
Editada: Voss
el 15 de Feb. de 2024
Yes, the name of the variable, not the value of the variable. Name implies it's in quotes, when using function syntax! Did you follow the example I ran through in this comment?
Respuesta aceptada
Voss
el 15 de Feb. de 2024
Use:
~exist("strF","var")
2 comentarios
Voss
el 15 de Feb. de 2024
You must supply exist with the name of the variable to check for.
This is what you were doing:
strF = "some_string";
% this checks for a variable called "some_string", which is the value of
% strF, but no variable called "some_string" exists
exist(strF,"var")
some_string = 99; % now "some_string" exists, so
exist(strF,"var") % this returns true (1)
As opposed to:
clear("strF") % clear strF
exist("strF","var") % strF doesn't exist now
strF = "some_string"; % now it does
exist("strF","var") % and exist shows that
some_string = 99; % and it doesn't matter about "some_string"
exist("strF","var") % because now exist is checking for a variable called "strF"
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