if i wanna read an input file with an equation in it, for example 2+3, and need to give the result of this input file, how should i write this code?:?:
joygqy
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Newbie Poster
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Jump to PostI hope I am understanding your question correctly. It seems to me that what you want to do is to evaluate an expression? If that is the case
- The expression as it stands is merely a string.
- You need to parse that expression - unlike VB and Javascript Delphi does …
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joygqy
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Newbie Poster
up up
ExplainThat
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Junior Poster in Training
I hope I am understanding your question correctly. It seems to me that what you want to do is to evaluate an expression? If that is the case
- The expression as it stands is merely a string.
- You need to parse that expression - unlike VB and Javascript Delphi does not have a built in eval function. It is worth typing in eval Delphi in Google to see if it comes up with anything useful.
- The technique for doing this is called Recursive Descent Parsing. I guess there is Pascal code for this somewhere out there.
- My personal preference would be to convert the expression to Reverse Polish Notation and then evaluate that. This is a great deal more elegant - and faster. I have an RPN evaluator written up some where - if I can dig it up I'll post a copy here.
Hope this helps.
Duoas
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Postaholic
Featured Poster
ExplainThat, this is a beginning programming school assignment. I really doubt the professor expects a recursive descent algorithm. Nor do I think he is permitted to redefine the shape of his input.
All the professor wants is some basic string parsing.
joygqy Show us some code, and we'll help you.
ExplainThat
1
Junior Poster in Training
Could be - like I said, I was not sure I had understood the question.
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