前缀、中缀、后缀表达式相互转换工具
目录
1. 界面一览
2. 使用说明
3. 实例演示
3.1 输入中缀
3.2 输入前缀
3.3 输入后缀
3.4 选择错误的类型
4. 代码
5. 资源地址
关于什么是前缀、中缀、后缀表达式，相信你不知道这个东西，那你也不会点进来这篇博客，当然，我刚刚也有写一个简单的介绍（前缀、中缀、后缀表达式介绍）。
1. 界面一览
2. 使用说明
你需要选择你输入的值是什么表达式类型，本来我是想要写一个自动检测输入的表达式是属于哪一种，但是奈何能力有限，搞了大半天都没搞出来，立即推，果断放弃，转换思路，让你自己选，总不能你自己都不知道你输的是啥吧哈哈哈。
在你输入得到时候，如果输入空格和中文的圆括号，后台会自动操作，不必担心，这也是为了方便自己，懒得输入法来回切换了，果然，懒惰是人类进步的动力。
上面黄色背景的是简单的举例，不用你自己再去算了，至于计算的功能，我没写，这个玩意随便一个 IDE 都能实现。
点击开始转换就会进行转换，根据你的选择的不同，会显示不同的结果，具体请看下面的实例演示。
输入值之后直接回车，也会触发转换，省去点击按钮的时间。
清空和关闭想必不用我多说了吧。
隐藏功能：这个功能会记住及上次移动的位置，不会每次都出现在固定的位置，方便每个人的操作。
3. 实例演示
3.1 输入中缀
3.2 输入前缀
3.3 输入后缀
3.4 选择错误的类型
4. 代码
using System;
using System.Collections.Generic;
using System.Windows.Forms;namespace TypeConversion
{public partial class frmChangeType : Form{public frmChangeType(){InitializeComponent();}/// <summary>/// 清空/// </summary>private void btnClear_Click(object sender, EventArgs e){txtInPut.Text = "";txtA2B.Text = "";lblA2B.Text = "待转换:";txtA2C.Text = "";lblA2C.Text = "待转换:";}/// <summary>/// 窗体加载/// </summary>private void Form1_Load(object sender, EventArgs e){cboType.Items.Add("前缀");cboType.Items.Add("中缀");cboType.Items.Add("后缀");cboType.SelectedIndex = 1;btnClear_Click(sender, e);txtInPut.KeyPress += txtInPut_KeyPress;// 将文本框的 KeyPress 事件与事件处理程序关联// 从应用程序设置中加载窗体位置if (Properties.Settings.Default.WindowLocation != null){this.Location = Properties.Settings.Default.WindowLocation;}}/// <summary>/// 窗体关闭自动保存上次窗体所在的位置/// </summary>protected override void OnFormClosing(FormClosingEventArgs e){base.OnFormClosing(e);// 保存窗体位置到应用程序设置Properties.Settings.Default.WindowLocation = this.Location;Properties.Settings.Default.Save();}/// <summary>/// 输入文本回车触发事件/// </summary>private void txtInPut_KeyPress(object sender, KeyPressEventArgs e){// 判断按下的键是否是回车键if (e.KeyChar == (char)Keys.Enter){btnChange_Click(sender, e);}}/// <summary>/// 转换按钮/// </summary>private void btnChange_Click(object sender, EventArgs e){// 获取当前选中的值string selectedValue = cboType.SelectedItem.ToString();// 记录返回结果string result;// 去除所有空格string sInPut = txtInPut.Text.Replace(" ", "");// 替换中文括号为英文括号sInPut = sInPut.Replace("（", "(").Replace("）", ")");if (sInPut == ""){MessageBox.Show("请输入值！", "警告", MessageBoxButtons.OK, MessageBoxIcon.Error);return;}ChangeMethods chmth = new ChangeMethods();try{if (selectedValue == "前缀"){result = chmth.ConvertPrefixToInfix(sInPut);lblA2B.Text = "前转中:";txtA2B.Text = result;result = chmth.ConvertPrefixToPostfix(sInPut);lblA2C.Text = "前转后:";txtA2C.Text = result;}else if (selectedValue == "中缀"){result = chmth.ConvertInfixToPrefix(sInPut);lblA2B.Text = "中转前:";txtA2B.Text = result;result = chmth.ConvertInfixToPostfix(sInPut);lblA2C.Text = "中转后:";txtA2C.Text = result;}else if (selectedValue == "后缀"){result = chmth.ConvertPostfixToPrefix(sInPut);lblA2B.Text = "后转前:";txtA2B.Text = result;result = chmth.ConvertPostfixToInfix(sInPut);lblA2C.Text = "后转中:";txtA2C.Text = result;}}catch (Exception ex){MessageBox.Show(ex.Message, "警告", MessageBoxButtons.OK, MessageBoxIcon.Information);}}/// <summary>/// 关闭按钮/// </summary>private void btnClose_Click(object sender, EventArgs e){Close();}}
}/// <summary>
/// 转换的具体方法
/// </summary>
public class ChangeMethods
{public bool IsOperand(char c){return Char.IsLetterOrDigit(c);}/// <summary>/// 判定操作数/// </summary>public bool IsOperator(char c){return c == '+' || c == '-' || c == '*' || c == '/';}/// <summary>/// 前转中/// </summary>public string ConvertPrefixToInfix(string sInPut){Stack<string> stack = new Stack<string>();try{// 从右到左遍历前缀表达式for (int i = sInPut.Length - 1; i >= 0; i--){char c = sInPut[i];if (IsOperator(c)){// 弹出两个操作数string operand1 = stack.Pop();string operand2 = stack.Pop();// 构建中缀表达式string infix = "(" + operand1 + c + operand2 + ")";// 将中缀表达式入栈stack.Push(infix);}else{// 将操作数入栈stack.Push(c.ToString());}}// 栈顶元素即为转换后的中缀表达式return stack.Pop();}catch (Exception ex){throw new Exception("前缀表达式转中缀表达式时发生异常: " + ex.Message);}}/// <summary>/// 前转后/// </summary>public string ConvertPrefixToPostfix(string sInPut){Stack<string> stack = new Stack<string>();try{// 从右到左遍历前缀表达式for (int i = sInPut.Length - 1; i >= 0; i--){char c = sInPut[i];if (IsOperator(c)){// 弹出两个操作数string operand1 = stack.Pop();string operand2 = stack.Pop();// 构建后缀表达式string postfix = operand1 + operand2 + c;// 将后缀表达式入栈stack.Push(postfix);}else{// 将操作数入栈stack.Push(c.ToString());}}// 栈顶元素即为转换后的后缀表达式return stack.Pop();}catch (Exception ex){throw new Exception("前缀表达式转后缀表达式时发生异常: " + ex.Message);}}/// <summary>/// 中转前/// </summary>public string ConvertInfixToPrefix(string infixExpression){Stack<char> operatorStack = new Stack<char>();Stack<string> operandStack = new Stack<string>();try{// 遍历中缀表达式for (int i = 0; i < infixExpression.Length; i++){char c = infixExpression[i];if (c == ' '){continue;}else if (Char.IsLetterOrDigit(c)){// 操作数直接入栈operandStack.Push(c.ToString());}else if (c == '('){// 左括号直接入栈operatorStack.Push(c);}else if (c == ')'){// 右括号，弹出操作符和操作数，构建前缀表达式while (operatorStack.Count > 0 && operatorStack.Peek() != '('){char op = operatorStack.Pop();string operand2 = operandStack.Pop();string operand1 = operandStack.Pop();string prefix = op + operand1 + operand2;operandStack.Push(prefix);}// 弹出左括号operatorStack.Pop();}else{// 操作符，根据优先级处理while (operatorStack.Count > 0 && operatorStack.Peek() != '(' && GetOperatorPriority(c) <= GetOperatorPriority(operatorStack.Peek())){char op = operatorStack.Pop();string operand2 = operandStack.Pop();string operand1 = operandStack.Pop();string prefix = op + operand1 + operand2;operandStack.Push(prefix);}// 当前操作符入栈operatorStack.Push(c);}}// 处理剩余的操作符和操作数while (operatorStack.Count > 0){char op = operatorStack.Pop();string operand2 = operandStack.Pop();string operand1 = operandStack.Pop();string prefix = op + operand1 + operand2;operandStack.Push(prefix);}// 栈顶元素即为转换后的前缀表达式return operandStack.Pop();}catch (Exception ex){throw new Exception("中缀表达式转前缀表达式时发生异常: " + ex.Message);}}/// <summary>/// 中转后/// </summary>public string ConvertInfixToPostfix(string infixExpression){Stack<char> operatorStack = new Stack<char>();List<string> postfixList = new List<string>();try{// 遍历中缀表达式for (int i = 0; i < infixExpression.Length; i++){char c = infixExpression[i];if (c == ' '){continue;}else if (Char.IsLetterOrDigit(c)){// 操作数直接加入后缀表达式列表postfixList.Add(c.ToString());}else if (c == '('){// 左括号直接入栈operatorStack.Push(c);}else if (c == ')'){// 右括号，弹出操作符，将操作符加入后缀表达式列表while (operatorStack.Count > 0 && operatorStack.Peek() != '('){postfixList.Add(operatorStack.Pop().ToString());}// 弹出左括号operatorStack.Pop();}else{// 操作符，根据优先级处理while (operatorStack.Count > 0 && operatorStack.Peek() != '(' && GetOperatorPriority(c) <= GetOperatorPriority(operatorStack.Peek())){postfixList.Add(operatorStack.Pop().ToString());}// 当前操作符入栈operatorStack.Push(c);}}// 将剩余的操作符加入后缀表达式列表while (operatorStack.Count > 0){postfixList.Add(operatorStack.Pop().ToString());}// 将后缀表达式列表转换为字符串string postfixExpression = string.Join("", postfixList);return postfixExpression;}catch (Exception ex){throw new Exception("中缀表达式转后缀表达式时发生异常: " + ex.Message);}}/// <summary>/// 后转前/// </summary>public string ConvertPostfixToPrefix(string postfixExpression){Stack<string> stack = new Stack<string>();try{// 遍历后缀表达式for (int i = 0; i < postfixExpression.Length; i++){char c = postfixExpression[i];if (IsOperator(c)){// 弹出两个操作数string operand2 = stack.Pop();string operand1 = stack.Pop();// 构建前缀表达式string prefix = c + operand1 + operand2;// 将前缀表达式入栈stack.Push(prefix);}else{// 将操作数入栈stack.Push(c.ToString());}}// 栈顶元素即为转换后的前缀表达式return stack.Pop();}catch (Exception ex){throw new Exception("后缀表达式转前缀表达式时发生异常: " + ex.Message);}}/// <summary>/// 后转中/// </summary>public string ConvertPostfixToInfix(string postfixExpression){Stack<string> stack = new Stack<string>();try{// 遍历后缀表达式for (int i = 0; i < postfixExpression.Length; i++){char c = postfixExpression[i];if (IsOperator(c)){// 弹出两个操作数string operand2 = stack.Pop();string operand1 = stack.Pop();// 构建中缀表达式string infix = "(" + operand1 + c + operand2 + ")";// 将中缀表达式入栈stack.Push(infix);}else{// 将操作数入栈stack.Push(c.ToString());}}// 栈顶元素即为转换后的中缀表达式return stack.Pop();}catch (Exception ex){throw new Exception("后缀表达式转中缀表达式时发生异常: " + ex.Message);}}/// <summary>/// 获取操作数优先级/// </summary>public int GetOperatorPriority(char op){switch (op){case '+':case '-':return 1;case '*':case '/':return 2;default:return 0;}}
}
5. 资源地址
代码