支持+-*/()int 型数据的计算机c++实现

  1 #include <iostream>
  2 #include<sstream>
  3 using namespace std;
  4 template<typename T>
  5 class stack
  6 {
  7     T p[40];
  8     int toop;
  9 public:
 10     stack() { toop = -1; }
 11     void push(T t) { toop++; p[toop] = t; }
 12     T top() { return p[toop]; }
 13     bool empty() { if (toop == -1)return true; return false; }
 14     void pop() { toop--; }
 15 };
 16 class caculator
 17 {
 18     string s;//原波兰式的容器
 19     stack<char>op;
 20     stack<float>num;
 21     stringstream ss;//用于转换的流
 22     stringstream sb;//插入逆波兰式的流
 23     string str;//存放数字的容器，每次更新
 24     string strs;//存放逆波兰式的容器
 25     float x, y;
 26 public:
 27     caculator(char *p) { s = p; }
 28     float trans(const char *p);
 29     float antipoland();
 30     void show() { cout << strs; }
 31     void readnum();
 32     void caucEveTime();
 33     void shownum() { while (!num.empty()) { cout << num.top() << endl; num.pop(); } }
 34     void showop() { while (!op.empty()) { cout << op.top() << endl; op.pop(); } }
 35 };
 36 float caculator::trans(const char *p)//底层const,对象为常量
 37 {
 38     float n;
 39     n = *p - ‘\0‘ - 48;//确保转化成int后数值不变
 40     int i = strlen(p);
 41     while (--i)
 42     {
 43         *p++;
 44         n = n * 10 + (*p - ‘\0‘ - 48);
 45     }
 46     return n;
 47 }
 48 void  caculator::readnum()
 49 {
 50     str = ss.str();
 51     if (!str.empty())//str中存放数字串
 52     {
 53         ss.str("");//清空流
 54         num.push(trans(str.c_str()));
 55     }
 56 }
 57 void caculator::caucEveTime()//由符号栈弹出符号决定调用
 58 {
 59     y = num.top();
 60     num.pop();
 61     x = num.top();
 62     num.pop();
 63     switch (op.top())
 64     {
 65     case‘+‘:num.push(x + y); break;
 66     case‘-‘:num.push(x - y); break;
 67     case‘*‘:num.push(x*y); break;
 68     case‘/‘:num.push(x / y); break;
 69     default:break;
 70     }
 71 }
 72 float caculator::antipoland()
 73 {
 74     for (int i = 0; i < s.size(); i++)
 75     switch (s[i])
 76     {
 77     case ‘(‘:op.push(s[i]);readnum(); break;
 78     case ‘+‘:
 79     case ‘-‘:
 80         readnum();
 81     if (op.top() == ‘(‘)
 82     op.push(s[i]);
 83     else if(op.empty())
 84         op.push(s[i]);
 85     else
 86     {
 87     while (!op.empty())
 88     {
 89         if (op.top() != ‘(‘&&op.top() != ‘)‘)
 90         {
 91             sb << op.top();
 92             caucEveTime();
 93         }
 94         op.pop();
 95     }
 96     op.push(s[i]);
 97     }
 98     break;
 99     case ‘)‘:
100         readnum();
101     while (op.top() != ‘(‘)
102     {
103        sb << op.top();
104        caucEveTime();
105        op.pop();
106     }op.pop(); break;
107     case ‘*‘:
108     case‘/‘:
109         readnum();
110     while (op.top() == ‘*‘ || op.top() == ‘/‘)
111     {
112        sb << op.top();
113        caucEveTime();
114        op.pop();
115     }op.push(s[i]); break;
116     default:
117     sb << s[i];
118     ss <<s[i];
119     break;
120     }
121     str = ss.str();
122     num.push(trans(str.c_str()));
123     while (!op.empty())
124     {
125         if (op.top() != ‘(‘&&op.top() != ‘)‘)
126         {
127             sb<< op.top();
128             caucEveTime();
129         }
130          op.pop();
131     }
132
133     strs = sb.str();
134     return num.top();
135 }
136 void main()
137 {
138     char ch[40];
139     char *p=ch;
140     cin >> p;
141     caculator a(p);
142     //a.antipoland();//两次重复调用改变数字栈中的数字！
143     // a.show();
144      cout <<"="<<a.antipoland()<<endl;
145     // cout << endl;
146     //a.shownum();
147     //a.showop();
148 }