operator precedence special case about cparse HOT 7 CLOSED

Hello @grazba, this is called operator precedence.

What you are saying you want is for the operator "." to have greater precedence than the operator "+" meaning it will be evaluated first, as in:

• a*b + c*d

Where the "+" operator will be evaluated last.

In CParse the operator precedence of each operator is defined using the calculator::Default().opPrecedence API, e.g.:

OppMap_t& opp = calculator::Default().opPrecedence;
// Note: The smaller the number the smaller the precedence:
opp.add("*", 1);
opp.add("+", 2);

So in your case it is likely that the number associated with "." is greater than the number associated with "+". You will need to move one of them up or down.

There is a short section in Defining New Operations page about this. Maybe it can help you further.

In any case I hope this solves you problem, if not tell me.

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@grazba, one more thing. I have had another user wanting to use Visual Studio on his project. So I wrote some documentation based on your issue and his feedbacks in the Download and Setup page. If you have some minutes could you read it and see if what I wrote makes sense?

I ask this because I don't have a VS environment to test that.

Thanks in advance =]

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yeah that's exactly what i was suspecting hence the name of the issue but i was not sure so yeah thanks i will try to fix it and close the issue when done.

For the the visual studio part , yes i will check the doc out and get back to you 👍 !

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Ops, I did not notice the name hehe, sorry. In any case, this looks like the kind of problem that would be fixed by changing the precedence values. I might be wrong since these expressions are complex but if this doesn't work tell me.

Also, there is a function I use to debug this type of expressions the calculator::str() function. You can use it like this:

calculator c1("W(\"name1\").L(\"name2\") + W(\"name1\").L(\"name3\")");
std::string rpn = c1.str();
std::cout << rpn << std::endl;

The result will show the operands and operators in Reverse Polish Notation. This notation shows exactly the order that the operations will take place, e.g.:

• a b c + -

Would be the same as:

• a - (b + c)

I.e. each operator operates on the previous 2 operands immediately before it.

This might help to understand how the expressions are being interpreted internally.

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Thanks for the details it's pretty helpful for debugging indeed !

For the visual studio part, yes it is alright the only little detail is the note about c++ 11 support. The compiler always had issues with covering all of the standard , but since 2017 they are working hard on supporting c++ 11/14/17 and it should be 100% standard pretty soon, visual studio 2013 does support c++11 but doesn't support some features of the language in the case of CParse the only feature missing is reference qualifiers so i think the note should be check the compiler support of c++ features.

the precedence of operators did the trick everything is working smoothly, more features to add.

Thanks again !

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That's good @grazba and thanks for the feedback.

But give a little more details: this problem with the reference qualifiers causes the compilation to break or it works fine? Also, sorry to bother you with these questions =P.

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with VS2013 it won't compile , but deleting the "&&" after the function name (i forgot which one it was) will make it work just fine. The feature is available since VS2015 !

Here you can find details about standard support for visual studio maybe you can link it to the users :
support for c++ 11-14-17 with visual studio

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