MATLAB Answers


How to define a string variable in IF statement

Asked by Andrei Makarskiy on 15 Oct 2015
Latest activity Commented on by the cyclist
on 15 Oct 2015
I'm stuck with matlab on almost every simple step I used to work with pretty fast in PHP. How this piece of code inside my function makes me crazy:
matchStr = regexp(filename,'^([0-9\-])+-StockAndOptionQuoteFor([A-z]+)\.', 'tokens');
CurDate = matchStr{1,1}{1,1};
Ticker = matchStr{1,1}{1,2};
Matlab keeps telling "Undefined function or variable 'Ticker'." or The variable 'Ticker' might be used before it is defined! But it's a standard practice in PHP. How do I know which type of variable it would be, a string or double?
Ticker='' didn't help


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2 Answers

Answer by Andrei Makarskiy on 15 Oct 2015
Edited by Andrei Makarskiy on 15 Oct 2015
 Accepted Answer

global Ticker;
Inside the Function helped. But after the function stops running the global Ticker returns to '' in the workspace. I'm stuck.

  1 Comment

Using global variables is not considered good programming practice, and can cause problems. Add the variable to the function argument list instead.

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Answer by the cyclist
on 15 Oct 2015

Spoiler alert: Different languages have different syntax. :-)
Are you trying to check if a variable named "Ticker" exists, and then create it if it does not? Then use the exist function
if ~exist('Ticker','var')
Ticker = matchStr{1,1}{1,2};
In MATLAB, "~" means logical negation.


Thanks, Folks. Your advice helped. Moreover, I found the problem which set the Ticker to '' every time I called the function, since the statement global Ticker; reset the variable to empty. So, I took out this piece of code to a more appropriate place outside the function.
This is an example of Star Strider's comment about defining global variables being a generally bad practice. Debugging problems can be a challenge, because code that is "far away" and difficult to find can affect something local.

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