Also remember that the Parse method is relying on the culture of your operating system to perform the conversion, so try to change your code to num2 = double.Parse(textBox1.Text, CultureInfo.InvariantCulture); You might also consider to use the double.TryParse method for better exception handling.
Regular Expression evaluation can be done using DataTable.Compute method (from MSDN) : Computes the given expression on the current rows that pass the filter criteria. Try this: using System.Data;//import this namespace string math = “100 * 5 – 2”; string value = new DataTable().Compute(math, null).ToString();
For a simple calculator with only 5 operators (^, *, /, +, -) and no parentheses, you can do something like this. First, it is convenient to turn the string into an array of numbers and operators. Then, we go through the array looking for each operator in order of precedence, and applying the operator … Read more
How about SymPy? Their solver looks like what you need. Have a look at their source code if you want to build the library yourself…
The issue here is that input() returns a string in Python 3.x, so when you do your comparison, you are comparing a string and an integer, which isn’t well defined (what if the string is a word, how does one compare a string and a number?) – in this case Python doesn’t guess, it throws … Read more
If you want to display the results of calculations as rational numbers then the only 100% correct solution is to use rational arithmetic throughout all calculations, i.e. all intermediate values are stored as a pair of integers (numerator, denominator), and all additions, multiplications, divisions, etc are done using the rules for rational numbers. As soon … Read more
According the htop source code, my assumptions looks like they are valid: (see static inline double LinuxProcessList_scanCPUTime(LinuxProcessList* this) function at LinuxProcessList.c) // Guest time is already accounted in usertime usertime = usertime – guest; # As you see here, it subtracts guest from user time nicetime = nicetime – guestnice; # and guest_nice from nice … Read more
The issue here is that input() returns a string in Python 3.x, so when you do your comparison, you are comparing a string and an integer, which isn’t well defined (what if the string is a word, how does one compare a string and a number?) – in this case Python doesn’t guess, it throws … Read more
pow() returns numbers as floating point. What is really returning is 24.99997 or something similar. But then you truncate it by assigning it to an integer and it comes out as 24. It’s ok to assignit to an integer in this case because you know then answer will always be an integer so you need … Read more
A pretty good approach would involve two steps. The first step involves converting the expression from infix to postfix (e.g. via Dijkstra’s shunting yard) notation. Once that’s done, it’s pretty trivial to write a postfix evaluator.