c++栈实现简单计算器

/* 栈实现计算器，主要思路就是设置一个符号栈和一个数字栈，在字符串首尾各加一个'#',然后扫描字符串， * 如果是数字进数字栈，如果是运算符号先判断符号优先级，若栈外符号优先级大于栈内符号优先级则进栈， * 小于栈内优先级则符号栈出栈一位，数字栈出栈两位进行计算，结果重新存进数字栈，直到栈外优先级大于栈内， */#include <iostream>#include <string>#include <algorithm>#include <cmath> using namespace std;const int MAX = 30;const int DONE = 1;/* run this program using the console pauser or add your own getch, system("pause") or input loop *///栈定义 template <class T>class Stack{public:Stack(int MaxStackSize=10);~Stack() { delete [] stack;}bool IsEmpty() const {return top==-1;}bool IsFull() const {return top==MaxTop;}T Top() const;Stack<T>& Add(const T& x);Stack<T>& Del(T& x);void MakeEmpty(){top=-1;} //清空栈void print(){for(int i; i < top + 1; i ++){cout<<stack[i]<<'\t';}cout<<endl;}private:int top;//栈顶int MaxTop;//最大的栈顶值T *stack;//堆栈元素数组};template<class T>Stack<T>::Stack(int MaxStackSize){MaxTop=MaxStackSize-1;stack=new T[MaxStackSize];top=-1;}template<class T>Stack<T>& Stack<T>::Add(const T& x){if(IsFull()){cout<<"no memory;"<<endl;return *this;}top=top+1;stack[top]=x;return *this;    }template<class T>Stack<T>& Stack<T>::Del(T& x){if(IsEmpty()){cout<<"no element"<<endl;return *this;}x=stack[top];top=top-1;return *this;}template<class T>T Stack<T>::Top() const{return stack[top];}//判断一个字符是否为数字bool isNum(char c){if((c > '0'||c == '0')&&(c < '9'||c == '9'))return true;elsereturn false;}//删除字符串中的空格 void deleteBlank(string &s){string::iterator i = s.begin();while ((i=find(i, s.end(), ' '))!=s.end())        s.erase(i);} //计算器class Calculator{public:Calculator(string s);~Calculator();int outPriority(char);      //返回栈外优先级int inPriority(char);       //返回栈内优先级 bool judgePri(char, char);  //判断优先级 前一个为栈外符号，后一个为栈内符号 若前大于后返回1，否则返回0 int judgePri(char);         //判断运算符  若是'#'返回 -1，若是')'返回 0，否则返回 1 void dealNum();     //处理数据int calculate();            //计算 void setString(string const s){this->s = '#' + s + '#';deleteBlank(this->s);   //删除字符串中的空格 }private:Stack<char> *s_sym;         //符号栈 Stack<int> *s_num;          //数据栈 string s;};Calculator::Calculator(string s){this->s = '#' + s + '#';deleteBlank(this->s);s_sym = new Stack<char>(MAX);s_num = new Stack<int>(MAX);} Calculator::~Calculator(){delete s_sym;delete s_num;}int Calculator::outPriority(char symble){switch(symble){case '#':return 0;case '(':return 8;case '+':return 2;case '-':return 2;case '*':return 4;case '/':return 4;case '%':return 4;case '^':return 6;case ')':return 1;default:throw 1;}}int Calculator::inPriority(char symble){switch(symble){case '#':return 0;case '(':return 1;case '+':return 3;case '-':return 3;case '*':return 5;case '/':return 5;case '%':return 5;case '^':return 7;case ')':return 8;default:throw 1;}}bool Calculator::judgePri(char out, char in){if(outPriority(out) > inPriority(in))return true;else return false;} int Calculator::judgePri(char symble){if(symble == '#')return -1;else if(symble == ')')return 0;elsereturn 1;}void Calculator::dealNum(){//将数据栈中的前两个弹出进行计算，结果放回数据栈，符号栈弹出顶部元素 char _temp = 0; int dtemp1 = 0;int dtemp2 = 0; s_sym->Del(_temp);s_num->Del(dtemp1);s_num->Del(dtemp2); switch(_temp){case '+':dtemp2 += dtemp1;break;case '-':dtemp2 = dtemp2 - dtemp1;break;case '*':dtemp2 = dtemp2 * dtemp1;break;case '/':if(dtemp1 == 0)throw 0;elsedtemp2 = dtemp2 / dtemp1;break;case '%':dtemp2 = dtemp2 % dtemp1;break;case '^':dtemp2 = pow(dtemp2,dtemp1);break;default:throw 1;}s_num->Add(dtemp2);}int Calculator::calculate(){  for(int i = 0; i < s.size(); i ++){   //遍历字符串 if(isNum(s[i])){int temp = (int)(s[i]) - 48;  //char强制类型转换为int ascii 码数值，减 48 转换为对应整数值 int _temp = 0;if(i > 0 && isNum(s[i - 1])){s_num->Del(_temp);temp = _temp * 10 + temp;}s_num->Add(temp);}else{ char temp = s[i];if(s_sym->IsEmpty()){s_sym->Add(temp);}else{if(judgePri(temp, s_sym->Top())){s_sym->Add(temp);  }else   if(judgePri(temp) == 1){          //栈外优先级小于栈内优先级，且不为 '#' 和 ')' while(!judgePri(temp, s_sym->Top())){ //当栈外优先级比栈内优先级低时，执行栈内符号运算 dealNum();}s_sym->Add(temp);}else if (judgePri(temp) == -1){while(s_sym->Top() != '#'){dealNum();}int result = s_num->Top();s_sym->MakeEmpty();s_num->MakeEmpty();return result;}else if(judgePri(temp) == 0){while(s_sym->Top() != '('){dealNum();}s_sym->Del(temp);}}}}}int main(int argc, char** argv) {try{string s = "";Calculator c(s);while(DONE){s = "";cout<<"请输入一个表达式"<<endl;getline(cin, s);   c.setString(s);int result = 0;    result = c.calculate();    cout<<c.calculate()<<endl;    system("pause");    system("cls");}}    catch(int i){    if(i == 0)    cout<<"除数不能为0！";    else if(i == 1)    cout<<"存在无法识别的符号！"<<endl;} return 0;}