Substring block returns incorrect value

Problem

I'm trying out the new "String" blocks available in R2018 and have found some behaviour that I can't explain. I'm trying to extract values from a string that I've created which looks like "D = (500,500,500). I've tried to do this inside a masked subsystem. Parameters for it are prefix (the symbol that indicates the start of the data I'm interested in), offset (how far after the prefix is the first character to return), num_chars (how many characters to return)

In order to get the first value I find the index of the "(" symbol using the String Find block, add an offset (of 1) to the index and then use the Substring block to get three characters from the string starting at the specified index. However sometimes this correctly returns "500" other times it returns "00,".

How I've been able to replicate the issue

If I change the value of the offset to zero it correctly returns "(50".

I then change the offset back to 1 and it correctly returns "500", result of the addition of the offset is 6 is this time.

The next time I run the simulation, it incorrectly returns "00," again. Result of the addition of the offset is now 7.

The output of the String Find block seems to change despite the string nor the substring changing.

Any ideas? Is this a bug?

Answer 1

[Arvindhan Sayapathy]

I am a MathWorks staff. This is a bug and I have forwarded this feedback to the relevant team.

[Scott]

Thanks for reporting it.