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Using GCMathParser for iphone development

开发者 https://www.devze.com 2023-02-01 11:44 出处:网络
I am trying to use GCMathParser in my iPhone application. To compile it, I changed #import <Cocoa/Cocoa.h> to #import <UIKit/UIKit.h> and replaced pi with M_PI and successfully compiled th

I am trying to use GCMathParser in my iPhone application. To compile it, I changed #import <Cocoa/Cocoa.h> to #import <UIKit/UIKit.h> and replaced pi with M_PI and successfully compiled the codes.

It works basically fine, but when I input wrong syntax like 3.3.3 or 3.. , I get syntax error as I am supposed to. But the next time I parse a very simple formula such as 5 , I still get syntax error for that. I made sure to allocate new instance to make开发者_StackOverflow社区 sure it starts new, but still i get it. Does anyone have the same issue?


There seems to be a bug in the GCMathParser; however there is a way around. There is a fixed pattern : when a malformed expression is fed into the parser an exception is raised. Right after that even if a well formed expression is fed, the exception is raised again. The key point is to evaluate the well formed expression twice. First check if an exception was raised; if YES simply reevaluate the same expression. Upon evaluating the well formed expression the second time, exception is not raised.Voila!

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