I'm currently making a calculator. I know how to write the logic but I'm curious if it can be done the way I'm going to explain.
String str = "12 + 43 * (12 / 2)";
int answer;
answer = str.magic();
//str.magic is the same as
answer = 12 + 43 * (12 / 2);
now what I want is how I can turn str into executible code.
You can use CodeDom to get a 'native' C# parser. (You should improve the error handling.)
using System.CodeDom.Compiler;
using Microsoft.CSharp;
using System.Reflection;
...
static void Main()
{
double? result = Calculate("12 + 43 * (12 / 2)");
}
static double? Calculate(string formula)
{
double result;
try
{
CompilerParameters compilerParameters = new CompilerParameters
{
GenerateInMemory = true,
TreatWarningsAsErrors = false,
GenerateExecutable = false,
};
string[] referencedAssemblies = { "System.dll" };
compilerParameters.ReferencedAssemblies.AddRange(referencedAssemblies);
const string codeTemplate = "using System;public class Dynamic {{static public double Calculate(){{return {0};}}}}";
string code = string.Format(codeTemplate, formula);
CSharpCodeProvider provider = new CSharpCodeProvider();
CompilerResults compilerResults = provider.CompileAssemblyFromSource(compilerParameters, new string[]{code});
if (compilerResults.Errors.HasErrors)
throw new Exception();
Module module = compilerResults.CompiledAssembly.GetModules()[0];
Type type = module.GetType("Dynamic");
MethodInfo method = type.GetMethod("Calculate");
result = (double)(method.Invoke(null, null));
}
catch (Exception)
{
return null;
}
return result;
}
You can simply use NCalc library Click here for more information. you can download that dll file from here
Example:
NCalc.Expression exp= new NCalc.Expression("(12*3)-29");
object obj = exp.Evaluate();
MessageBox.Show(obj.ToString());
