C# 表达式计算器----数据结构
using System;
using System.Collections.Generic;
using System.Linq; using System.Text;
using System.Collections;
namespace ConsoleApplication7
{
class Calculator
{
static void Main(string[] args)
{
//string exp = "345*2^(4+2*2-1*3)-5";
for (; ; )
{
Console.WriteLine("input a values:");
string exp = Console.ReadLine();
Console.WriteLine("output reslut:");
Console.WriteLine(Calculate(exp));
Console.WriteLine("END"); }
// string exp = "130+20";
//Console.ReadKey(); }
public static double Calculate(string _exp)
{ Stack operandStack = new Stack();//操作数
Stack operatorStack = new Stack();//运算符
operatorStack.Push('#');
char[] exp = (_exp + "#").ToCharArray();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < exp.Length; i++)
{
if (IsPerand(exp[i]))
{
sb.Append(exp[i]);
}
else
{
string sbstr = sb.ToString();
if (sbstr!="")
{
operandStack.Push(sb);
}
sb = new StringBuilder();
//优先级大于当前栈顶运算符的优先级
if (PriorityBeforeIn(exp[i]) > priorityAferIn((char)operatorStack.Peek()))
{
operatorStack.Push(exp[i]);//#*
}
else if (PriorityBeforeIn(exp[i]) < priorityAferIn((char)operatorStack.Peek()))
{
object sbd =operandStack.Pop();
string str = sbd.ToString();
object sbd1 =operandStack.Pop();
string str1 = sbd1.ToString();
double dou= Convert.ToDouble(str);
double dou1= Convert.ToDouble(str1);
operandStack.Push(Count((char)operatorStack.Pop(),dou,dou1));
i--;
}
else if (PriorityBeforeIn(exp[i]) == priorityAferIn((char)operatorStack.Peek()))
{
if (exp[i] == ')')
{
while (true)
{
char c = (char)operatorStack.Peek();
if (c == '(')
{
operatorStack.Pop();
break;
}
object sbd = operandStack.Pop();
string str = sbd.ToString();
object sbd1 = operandStack.Pop();
string str1 = sbd1.ToString();
double dou = Convert.ToDouble(str);
double dou1 = Convert.ToDouble(str1);
operandStack.Push(Count((char)operatorStack.Pop(), dou, dou1));
} }
else if (exp[i] == '#')
{
while (true)
{
char c = (char)operatorStack.Peek();
if (c == '#')
{
operatorStack.Pop();
break;
}
object sbd = operandStack.Pop();
string str = sbd.ToString();
object sbd1 = operandStack.Pop();
string str1 = sbd1.ToString();
double dou = Convert.ToDouble(str);
double dou1 = Convert.ToDouble(str1);//出错
operandStack.Push(Count((char)operatorStack.Pop(), dou, dou1));
} } } }
}
return (double)operandStack.Pop();
}
//判断字符是否为操作数
private static bool IsPerand(char c)
{ bool flag = false;//不执行
switch (c)
{
case'.':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
flag = true;
break;
}
return flag;
}
//获取操作符入栈前的优先级
private static int PriorityBeforeIn(char _opertor)
{
int priority = -1;
switch (_opertor)
{
case '#':
priority = 0;
break;
case '(':
priority = 8;
break;
case '^':
priority = 6;
break;
case '*':
case '/':
case '%':
priority = 4;
break;
case '+':
case '-':
priority = 2;
break;
case ')':
priority = 1;
break;
default:
break;
}
return priority;
}
//获取操作符入站后的优先级
private static int priorityAferIn(char _operator)
{
int priority = -1;
switch (_operator)
{
case '#':
priority = 0;
break;
case '(':
priority = 1;
break;
case '^':
priority = 7;
break;
case '*':
case '/':
case '%':
priority = 5;
break;
case '+':
case '-':
priority = 3;
break;
case ')':
priority = 8;
break;
default:
break;
}
return priority;
}
//按照指定操作对两个数字进行相应的计算
private static double Count(char _operator, double a, double b)
{
double result = 0;
switch (_operator)
{
case '^':
result = (double)Math.Pow(b, a);
break;
case '*':
result = b * a;
break;
case '/':
result = b / a;
break;
case '%':
result = b % a;
break;
case '+':
result = b + a;
break;
case '-':
result = b - a;
break;
default:
break;
} return result;
}
}
}
