头文件:
#pragma once #include <iostream> #include <assert.h> #include <string> using namespace std; template<class Type> class SeqStack { public: SeqStack(size_t sz = INIT_SZ); ~SeqStack(); public: bool empty()const; bool full()const; void show()const; bool push(const Type &x); bool pop(); void gettop(Type &x); int length()const; void clear(); void destory(); void quit_system(Type &x); private: enum{ INIT_SZ = 64 }; Type *base; int capacity; int top; }; template<class Type> SeqStack<Type>::SeqStack(size_t sz = INIT_SZ) { capacity = sz > INIT_SZ ? sz : INIT_SZ; base = new Type[capacity]; assert(base != NULL); top = 0; } template<class Type> SeqStack<Type>::~SeqStack() { destory(); } // 判断栈是否满了 template<class Type> bool SeqStack<Type>::full()const { return (top >= capacity); } // 判断是否为空栈 template<class Type> bool SeqStack<Type>::empty()const { return (top == 0); } // 显示 template<class Type> void SeqStack<Type>::show()const { if (top == 0) { cout << "the stack is empty!" << endl; return; } for (int i = top - 1; i >= 0; --i) { cout << base[i] << endl; } } // 入栈 template<class Type> bool SeqStack<Type>::push(const Type &x) { if (full()) { cout << "the stack is full,can not enter!" << endl; return false; } else { base[top] = x; top++; return true; } } // 出栈 template<class Type> bool SeqStack<Type>::pop() { if (empty()) { cout << "the stack is empty,can not pop!" << endl; return false; } else { top--; return true; } } // 获得栈顶元素 template<class Type> void SeqStack<Type>::gettop(Type &x) { x = base[top - 1]; } // 求栈长度 template<class Type> int SeqStack<Type>::length()const { return top; } // 清空栈 template<class Type> void SeqStack<Type>::clear() { top = 0; } // 摧毁栈 template<class Type> void SeqStack<Type>::destory() { delete[]base; base = NULL; capacity = top = 0; } // 退出系统 template<class Type> void SeqStack<Type>::quit_system(Type &x) { x = 0; }
主函数:
#include "exp.h" #include "exp.h" //检查符号之间的优先级,1表示>,0表示=,-1表示<,c1栈内的运算,c2栈外的运算 int check(char c1, char c2) { int a1, a2; if (c1 == '+' || c1 == '-') a1 = 3; if (c1 == '*' || c1 == '/') a1 = 5; if (c1 == '(') a1 = 1; if (c1 == ')') a1 = 7; if (c1 == '#') a1 = 0; if (c2 == '+' || c2 == '-') a2 = 2; if (c2 == '*' || c2 == '/') a2 = 4; if (c2 == '(') a2 = 6; if (c2 == ')') a1 = 1; if (c2 == '#') a2 = 0; if (a1 > a2) return 1; if (a1 == a2) return 0; if (a1 < a2) return -1; } //符号运算函数 double sum(char c, double d1, double d2) { switch (c) { case '+': return d1 + d2; break; case '-': return d1 - d2; break; case '*': return d1 * d2; break; case '/': return d1 / d2; break; default: break; } } int main() { char *op = "+-*/()#"; string str; cin >> str; //给表达式字符串str添加‘#’结束标志符 str.append(1, '#'); SeqStack<char> OPTR;//运算符栈 SeqStack<double> OPND;//操作数栈 int a = -1; //先将'#'入栈 OPTR.push('#'); while (true) { int b = a + 1; a = str.find_first_of(op, a + 1); if (a == string::npos) break; if (a != b) { string ss(str, b, a - b); double d = atof(ss.c_str()); //数据先入栈 OPND.push(d); } //运算符优先级比较 char val; OPTR.gettop(val); int che = check(val, str[a]); if (-1 == che)//栈外优先级大直接入栈 { OPTR.push(str[a]); } if (0 == che)//栈内外优先级相等则出栈 { OPTR.pop(); } if (1 == che)//栈内优先级大,出栈进行运算 { char val; OPTR.gettop(val); double d1; OPND.gettop(d1); OPND.pop(); double d2; OPND.gettop(d2); OPND.pop(); d1 = sum(val, d2, d1); //运算结果入栈 OPND.push(d1); OPTR.pop(); a--; } } double s; OPND.gettop(s); cout << s << endl; return 0; }
原文地址:http://blog.csdn.net/zhaoyaqian552/article/details/46424097