On 22/03/12 22:14, Sukhpreet Sdhu wrote:
i want to write a program that reads simple arithematic expressions and calculates the result.
OK, there are many ways to do this but they pretty much fall into three categories: 1) read the string and exec() it - easy but very risky from a security point of view. 2) Write a general text parser to break the input string into operands and operators and combine the results. 3) build a state machine that looks for valid input (this will be easier if you opt for reverse polish notation BTW) You can do No 1 real quick just for fun, but don't try that in a real world program. So that leaves 2 and 3. If you understand the concepts (or research them on wikipedia) you can have at it, write some code and lets see what you get to. Hint: Start with a limited subset - only 2 operands and one operator allowed, say. HTH -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
