C++ Stack实现四则运算

calculator.cpp

#include <iostream>
#include <stack>

using namespace std;

int Priority(char ch)
{
	switch(ch)
	{
		case '(':
			return 3;
		case '*':
		case '/':
			return 2;
		case '+':
		case '-':
			return 1;
		default:
			return 0;
	}	
}

int main()
{	
	int i = 0, tmp = 0, num1, num2, result;
	stack<int> s_opt, s_num;
	char opt[64] = {0};
	char ch;

	cout << "Please input :" << endl;
	cin >> opt;

	while (opt[i] != '\0' || s_opt.empty() != true)
	{
		if (opt[i] >= '0' && opt[i] <= '9')
		{
			tmp = tmp * 10 + opt[i] - '0';
			i++;
			if (opt[i] > '9' || opt[i] < '0')
			{
				s_num.push(tmp);
				tmp = 0;
			}
		}
		else
		{
			//操作符进栈
			if (s_opt.empty() || (s_opt.top() == '(' && opt[i] != ')') 
			|| Priority(opt[i]) > Priority(s_opt.top()))
			{
				s_opt.push(opt[i]);
				i++;
				continue;
			}

			if (s_opt.top() == '(' && opt[i] == ')')
			{	
				s_opt.pop();
				i++;
				continue;
			}

			if ((opt[i] == ')' && s_opt.top() != '(') || 
				Priority(opt[i]) <= Priority(s_opt.top()) || (opt[i] == '\0' && !s_opt.empty()))
			{
				ch = s_opt.top();	
				s_opt.pop();
				switch(ch)
				{
					case '+':
						num1 = s_num.top();
						s_num.pop();
						num2 = s_num.top();
						s_num.pop();
						s_num.push(num1 + num2);
						break;
					case '-':
						num1 = s_num.top();
						s_num.pop();
						num2 = s_num.top();
						s_num.pop();
						s_num.push(num2 - num1);
						break;
					case '*':
						num1 = s_num.top();
						s_num.pop();
						num2 = s_num.top();
						s_num.pop();
						s_num.push(num1 * num2);
						break;
					case '/':
						num1 = s_num.top();
						s_num.pop();
						num2 = s_num.top();
						s_num.pop();
						s_num.push(num2 / num1);
						break;
				}
			}
		}
	}
	result = s_num.top();

	cout << result << endl;
	return 0;
}

更多视频、文章、嵌入式学习资料，微信关注 【学益得智能硬件】