Re: Understanding recursive code

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From	Ben Bacarisse <ben.usenet@bsb.me.uk>
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Subject	Re: Understanding recursive code
Date	Wed, 10 Feb 2021 11:19:52 +0000
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Jonas Thörnvall <jonas.thornvall@gmail.com> writes:

> I had a look at my own recursive code, and realised i am not sure i
> get what actually break my recursion. Could someone explain.

What you have posted is not a complete example.  First, I have to guess
what the call is that you are debugging.  I've assumed it's

  evalPrimary(calcSTR);

Second, the code references undefined variables.  For example,
'evaluation' is used in conditional tests but is never set.  That's not
the only case of using undefined variables, but it's the most obvious.

Third, the almost exclusive use of global rather than local variables
makes it almost impossible for me to reason about what the code is
doing.  Every function call could, until I can prove otherwise, change
almost every variable referenced in the calling function.  I last
debugged such a program when I stopped being a research assistant
helping non-programmers using FORTRAN IV.  That was in 1979.  I don't
want to start again.  It's a grim job.

I know you will want to just plough on, hammering the code into shape,
but if you were a student of mine I would insist that you start again
with a well thought out high-level plan which can be written in code
without a single global variable.

<snip code>
-- 
Ben.

Thread

Understanding recursive code Jonas Thörnvall <jonas.thornvall@gmail.com> - 2021-02-10 01:36 -0800
  Re: Understanding recursive code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-02-10 11:19 +0000
    Re: Understanding recursive code Jonas Thörnvall <jonas.thornvall@gmail.com> - 2021-02-10 05:19 -0800
      Re: Understanding recursive code John G Harris <niam@jghnorth.org.uk.invalid> - 2021-02-10 18:01 +0000

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