1 #include <iostream>
 2 #include "stack.h"
 3 using namespace std;
 4 using namespace stack;
 5 template class Stack<int>;
 6 int main(void)
 7 {
 8     //（1.1*1.2+1.3*1.4）+（1.5*1.6^1.7^(1.8+1.9))
 9     calexp item[] = { ('('), (1.1), ('*'), (1.2), ('+'), (1.3), ('*'), (1.4), (')'), ('+'), ('('), (1.5), ('*'), (1.6), ('^'), (1.7), ('^'), ('('), (1.8), ('+'), (1.9), (')'), (')'), };
10     infix_to_postfix(item, sizeof(item)/sizeof(item[0]));
11     for (int i = 0; i < sizeof(item) / sizeof(item[0]); ++i)
12         item[i].showcalexp();
13     system("pause");
14 }

View Code

  1 //练习3.20新增，中缀表达式转后缀表达式，包含错误检测
  2 void infix_to_postfix(calexp item[], int size)
  3 {
  4     calexp* temp = new calexp[size];
  5     //初检模块
  6     //排除不以数据或正括号开头的表达式
  7     if (item[0].gettype() != CALEXP_NUMBER && item[0].getopera() != '(')
  8     {
  9         cout << "Error: illegal beginning" << endl;
 10         return;
 11     }
 12     //排除不以数据或反括号结尾的表达式
 13     if (item[size - 1].gettype() != CALEXP_NUMBER && item[size - 1].getopera() != ')')
 14     {
 15         cout << "Error: illegal ending" << endl;
 16         return;
 17     }
 18     for (int i = 0; i != size - 1; ++i)
 19     {
 20         //排除非法操作符
 21         if (item[i].gettype() == CALEXP_OPERATOR && item[i].getlevel() == 0)
 22         {
 23             cout << "Error: illegal operator" << endl;
 24             return;
 25         }
 26         //排除连续的数据
 27         //排除连续的操作符（除非至少有一个是正括号或反括号）
 28         if (item[i].gettype() == item[i + 1].gettype())
 29         {
 30             if (item[i].gettype() == CALEXP_NUMBER)
 31             {
 32                 cout << "Error: consecutive number" << endl;
 33                 return;
 34             }
 35             else
 36             {
 37                 if ((item[i].getlevel() != 4 && item[i].getlevel() != -1) && (item[i + 1].getlevel() != 4 && item[i + 1].getlevel() != -1))
 38                 {
 39                     cout << "Error: consecutive operators" << endl;
 40                     return;
 41                 }
 42             }
 43         }
 44     }
 45     //正式转换
 46     Stack<calexp> operators;
 47     operators.push(calexp('!'));
 48     int j = 0;
 49     for (int i = 0; i != size; ++i)
 50     {
 51         //元素为数值时，直接加入临时数组
 52         if (item[i].gettype() == CALEXP_NUMBER)
 53             temp[j++] = item[i];
 54         //元素为操作符时，进行相应的操作
 55         else
 56         {
 57             //如果即将加入的操作符等级比栈顶操作符等级更高
 58             //则无条件压入栈
 59             if (item[i].getlevel() > operators.getfirst().getlevel())
 60                 operators.push(item[i]);
 61             //如果即将加入的操作符等级比栈顶操作符等级更低或一致
 62             else
 63             {
 64                 //如果即将加入反括号
 65                 if (item[i].getlevel() == -1)
 66                 {
 67                     temp[j++] = item[i];
 68                     //无条件弹出操作符直到最近一个正括号被弹出
 69                     while (operators.getfirst().getlevel() != 0 && operators.getfirst().getlevel() != 4)
 70                         temp[j++] = operators.getpop();
 71                     if (operators.getfirst().getlevel() == 4)
 72                         temp[j++] = operators.getpop();
 73                     //如果在栈中未发现正括号则报错
 74                     else
 75                     {
 76                         cout << "Error: ( not found before )" << endl;
 77                         return;
 78                     }
 79                 }
 80                 //如果即将加入左结合的操作符（+,-,*,/)
 81                 else if (item[i].getlevel() == 1 || item[i].getlevel() == 2)
 82                 {
 83                     //那么弹出操作符直到空栈或发现正括号为止
 84                     while (operators.getfirst().getlevel() != 0 && operators.getfirst().getlevel() != 4)
 85                         temp[j++] = operators.getpop();
 86                     //把当前操作符压入
 87                     operators.push(item[i]);
 88                 }
 89                 //假如是左括号是右结合取幂操作符，无条件压入且暂时不取出
 90                 else
 91                     operators.push(item[i]);
 92             }
 93         }
 94     }
 95     //原表达式遍历完毕后，弹出操作符栈剩余符号
 96     while (operators.getfirst().getlevel() != 0)
 97     {
 98         //如果符号中残留正括号则报错
 99         if (operators.getfirst().getlevel() == 4)
100         {
101             cout << "Error: a ( without )" << endl;
102             return;
103         }
104         else
105             temp[j++] = operators.getpop();
106     }
107     //将临时数组复制回原数组
108     for (int i = 0; i != size; ++i)
109         item[i] = temp[i];
110     delete[] temp;
111 }