Evaluates arithmetic expression without evaluating variables.

Question

1.00/5 (3 votes)

See more:

I created a API to evaluate an expression. It takes expression like "100+200+Var1" and return as "300+var1" without evaluating variables since variable value not known.

But when i tried to evaluate expression like "100+var1+200" i can only return as "100+var1+200" but not "300+var1".

Is there any example which evaluates arithmetic expression without evaluating
variables.

What I have tried:

I searched google and found "NCalc - Mathematical Expressions Evaluator for .NET" to evaluate arithmetic expression with variables but it expects values for those variables
before running it.

Posted 6-Apr-16 2:01am

chankayudu

Updated 6-Apr-16 2:40am

Add a Solution

Comments

phil.o 6-Apr-16 8:15am

Maybe if you let us have a look at your evaluator we could try to help. Please show your actual code.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2016-04-06T02:40:00

You need to start looking at Operator associativity - Wikipedia, the free encyclopedia[^]
"+" is both left- and right- associative, so a + b + c can be evaluated in any order, so your evaluator would be free to assign a "fixed/variable" value to each part of the expression and rearrange it to "group" the fixed and variable parts:

100 + var1 + 200
 F  +  V   +  F
therefore:
100 + 200 + var1
 F  +  F  +  V
is equivalent

Exactly how you do that in your code I can't say: I have no idea of how it works. But consider adding an associativity property to your operators, and it should give you the beginnings of what you want.