मैंने इसे कुछ सप्ताह पहले सी # में व्यक्तिगत व्यायाम के रूप में किया था।
यह काफी कोड है और स्थानों पर खराब टिप्पणी की गई है। लेकिन यह कई परीक्षण मामलों के साथ काम किया।
का आनंद लें!
using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
namespace StackOverflow
{
class Start
{
public static void Main(string[] args)
{
Evaluator ev;
string variableValue, eq;
Console.Write("Enter equation: ");
eq = Console.ReadLine();
while (eq != "quit")
{
ev = new Evaluator(eq);
foreach (Variable v in ev.Variables)
{
Console.Write(v.Name + " = ");
variableValue = Console.ReadLine();
ev.SetVariable(v.Name, Convert.ToDecimal(variableValue));
}
Console.WriteLine(ev.Evaluate());
Console.Write("Enter equation: ");
eq = Console.ReadLine();
}
}
}
class EvalNode
{
public virtual decimal Evaluate()
{
return decimal.Zero;
}
}
class ValueNode : EvalNode
{
decimal value;
public ValueNode(decimal v)
{
value = v;
}
public override decimal Evaluate()
{
return value;
}
public override string ToString()
{
return value.ToString();
}
}
class FunctionNode : EvalNode
{
EvalNode lhs = new ValueNode(decimal.Zero);
EvalNode rhs = new ValueNode(decimal.Zero);
string op = "+";
public string Op
{
get { return op; }
set
{
op = value;
}
}
internal EvalNode Rhs
{
get { return rhs; }
set
{
rhs = value;
}
}
internal EvalNode Lhs
{
get { return lhs; }
set
{
lhs = value;
}
}
public override decimal Evaluate()
{
decimal result = decimal.Zero;
switch (op)
{
case "+":
result = lhs.Evaluate() + rhs.Evaluate();
break;
case "-":
result = lhs.Evaluate() - rhs.Evaluate();
break;
case "*":
result = lhs.Evaluate() * rhs.Evaluate();
break;
case "/":
result = lhs.Evaluate()/rhs.Evaluate();
break;
case "%":
result = lhs.Evaluate() % rhs.Evaluate();
break;
case "^":
double x = Convert.ToDouble(lhs.Evaluate());
double y = Convert.ToDouble(rhs.Evaluate());
result = Convert.ToDecimal(Math.Pow(x, y));
break;
case "!":
result = Factorial(lhs.Evaluate());
break;
}
return result;
}
private decimal Factorial(decimal factor)
{
if (factor < 1)
return 1;
return factor * Factorial(factor - 1);
}
public override string ToString()
{
return "(" + lhs.ToString() + " " + op + " " + rhs.ToString() + ")";
}
}
public class Evaluator
{
string equation = "";
Dictionary<string, Variable> variables = new Dictionary<string, Variable>();
public string Equation
{
get { return equation; }
set { equation = value; }
}
public Variable[] Variables
{
get { return new List<Variable>(variables.Values).ToArray(); }
}
public void SetVariable(string name, decimal value)
{
if (variables.ContainsKey(name))
{
Variable x = variables[name];
x.Value = value;
variables[name] = x;
}
}
public Evaluator(string equation)
{
this.equation = equation;
SetVariables();
}
public decimal Evaluate()
{
return Evaluate(equation, new List<Variable>(variables.Values));
}
public decimal Evaluate(string text)
{
decimal result = decimal.Zero;
equation = text;
EvalNode parsed;
equation = equation.Replace(" ", "");
parsed = Parse(equation, "qx");
if (parsed != null)
result = parsed.Evaluate();
return result;
}
public decimal Evaluate(string text, List<Variable> variables)
{
foreach (Variable v in variables)
{
text = text.Replace(v.Name, v.Value.ToString());
}
return Evaluate(text);
}
private static bool EquationHasVariables(string equation)
{
Regex letters = new Regex(@"[A-Za-z]");
return letters.IsMatch(equation);
}
private void SetVariables()
{
Regex letters = new Regex(@"([A-Za-z]+)");
Variable v;
foreach (Match m in letters.Matches(equation, 0))
{
v = new Variable(m.Groups[1].Value, decimal.Zero);
if (!variables.ContainsKey(v.Name))
{
variables.Add(v.Name, v);
}
}
}
#region Parse V2
private Dictionary<string, string> parenthesesText = new Dictionary<string, string>();
/*
* 1. All the text in first-level parentheses is replaced with replaceText plus an index value.
* (All nested parentheses are parsed in recursive calls)
* 2. The simple function is parsed given the order of operations (reverse priority to
* keep the order of operations correct when evaluating).
* a. Addition (+), subtraction (-) -> left to right
* b. Multiplication (*), division (/), modulo (%) -> left to right
* c. Exponents (^) -> right to left
* d. Factorials (!) -> left to right
* e. No op (number, replaced parentheses)
* 3. When an op is found, a two recursive calls are generated -- parsing the LHS and
* parsing the RHS.
* 4. An EvalNode representing the root node of the evaluations tree is returned.
*
* Ex. 3 + 5 (3 + 5) * 8
* + *
* /\ /\
* 3 5 + 8
* /\
* 3 + 5 * 8 3 5
* +
* /\
* 3 *
* /\
* 5 8
*/
/// <summary>
/// Parses the expression and returns the root node of a tree.
/// </summary>
/// <param name="eq">Equation to be parsed</param>
/// <param name="replaceText">Text base that replaces text in parentheses</param>
/// <returns></returns>
private EvalNode Parse(string eq, string replaceText)
{
int randomKeyIndex = 0;
eq = eq.Replace(" ", "");
if (eq.Length == 0)
{
return new ValueNode(decimal.Zero);
}
int leftParentIndex = -1;
int rightParentIndex = -1;
SetIndexes(eq, ref leftParentIndex, ref rightParentIndex);
//remove extraneous outer parentheses
while (leftParentIndex == 0 && rightParentIndex == eq.Length - 1)
{
eq = eq.Substring(1, eq.Length - 2);
SetIndexes(eq, ref leftParentIndex, ref rightParentIndex);
}
//Pull out all expressions in parentheses
replaceText = GetNextReplaceText(replaceText, randomKeyIndex);
while (leftParentIndex != -1 && rightParentIndex != -1)
{
//replace the string with a random set of characters, stored extracted text in dictionary keyed on the random set of chars
string p = eq.Substring(leftParentIndex, rightParentIndex - leftParentIndex + 1);
eq = eq.Replace(p, replaceText);
parenthesesText.Add(replaceText, p);
leftParentIndex = 0;
rightParentIndex = 0;
replaceText = replaceText.Remove(replaceText.LastIndexOf(randomKeyIndex.ToString()));
randomKeyIndex++;
replaceText = GetNextReplaceText(replaceText, randomKeyIndex);
SetIndexes(eq, ref leftParentIndex, ref rightParentIndex);
}
/*
* Be sure to implement these operators in the function node class
*/
char[] ops_order0 = new char[2] { '+', '-' };
char[] ops_order1 = new char[3] { '*', '/', '%' };
char[] ops_order2 = new char[1] { '^' };
char[] ops_order3 = new char[1] { '!' };
/*
* In order to evaluate nodes LTR, the right-most node must be the root node
* of the tree, which is why we find the last index of LTR ops. The reverse
* is the case for RTL ops.
*/
int order0Index = eq.LastIndexOfAny(ops_order0);
if (order0Index > -1)
{
return CreateFunctionNode(eq, order0Index, replaceText + "0");
}
int order1Index = eq.LastIndexOfAny(ops_order1);
if (order1Index > -1)
{
return CreateFunctionNode(eq, order1Index, replaceText + "0");
}
int order2Index = eq.IndexOfAny(ops_order2);
if (order2Index > -1)
{
return CreateFunctionNode(eq, order2Index, replaceText + "0");
}
int order3Index = eq.LastIndexOfAny(ops_order3);
if (order3Index > -1)
{
return CreateFunctionNode(eq, order3Index, replaceText + "0");
}
//no operators...
eq = eq.Replace("(", "");
eq = eq.Replace(")", "");
if (char.IsLetter(eq[0]))
{
return Parse(parenthesesText[eq], replaceText + "0");
}
return new ValueNode(decimal.Parse(eq));
}
private string GetNextReplaceText(string replaceText, int randomKeyIndex)
{
while (parenthesesText.ContainsKey(replaceText))
{
replaceText = replaceText + randomKeyIndex.ToString();
}
return replaceText;
}
private EvalNode CreateFunctionNode(string eq, int index, string randomKey)
{
FunctionNode func = new FunctionNode();
func.Op = eq[index].ToString();
func.Lhs = Parse(eq.Substring(0, index), randomKey);
func.Rhs = Parse(eq.Substring(index + 1), randomKey);
return func;
}
#endregion
/// <summary>
/// Find the first set of parentheses
/// </summary>
/// <param name="eq"></param>
/// <param name="leftParentIndex"></param>
/// <param name="rightParentIndex"></param>
private static void SetIndexes(string eq, ref int leftParentIndex, ref int rightParentIndex)
{
leftParentIndex = eq.IndexOf('(');
rightParentIndex = eq.IndexOf(')');
int tempIndex = eq.IndexOf('(', leftParentIndex + 1);
while (tempIndex != -1 && tempIndex < rightParentIndex)
{
rightParentIndex = eq.IndexOf(')', rightParentIndex + 1);
tempIndex = eq.IndexOf('(', tempIndex + 1);
}
}
}
public struct Variable
{
public string Name;
public decimal Value;
public Variable(string n, decimal v)
{
Name = n;
Value = v;
}
}
}
यह – rshimoda
पूछने के लिए धन्यवाद, आप http://Ncalc.codeplex.com पर भी देख सकते हैं जैसा कि मैंने अपने उत्तर में सुझाव दिया है, जो मुझे समझ में नहीं आ रहा है। – GreyCloud