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 - ' ' - 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 - ' ' - 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 }