c++加减乘除计算器
#include <iostream>
#include <>
#include <string>
void main()
{
char str[0xFF];
do
{
system("cls");
float a{};
float b{};
int count = 1;
int isOperating = -1;
bool isFirst = true;
std::string text{ "按任意键重置，继续计算\n" };
std::cout << "------计算机------\n";
std::cout << "请输入加减乘除：";
std::cin >> str;
for (int i = strlen(str) - 1; i >= 0; i--)
{
float* num = isFirst ? &b : &a;
switch (str[i])
{
case '*':
isOperating = 0;
break;
case '/':
isOperating = 1;
break;
case '+':
isOperating = 2;
break;
case '-':
isOperating = 3;
break;
}
if (!isFirst&&!isdigit(str[i])&& str[i]<=127&& str[i]>=0)
{
isOperating = 4;
text = "暂只支持正整数加减乘除，不能输入中文,其他符号或运算符\n按任意键重新输入\n";
break;
}
if (isOperating != -1 && count != 1 && isFirst)
{
isFirst = false;
count = 1;
if (i == 0 || i == strlen(str) - 1)
{
isOperating = 4;
break;
}
continue;
}
*num += ((int)str[i] - 48) * count;
count *= 10;
}
switch (isOperating)
{
case 0:
std::cout << "结果为:" << a * b << std::endl;
break;
case 1:
if (a == 0)
text = "除数不能为0\n按任意键重置，继续计算\n";
else
std::cout << "结果为:" << a / b << std::endl;
break;
case 2:
std::cout << "结果为:" << a + b << std::endl;
break;
case 3:
std::cout << "结果为:" << a - b << std::endl;
break;
default:
text = text == "按任意键重置，继续计算\n" ? "错误格式,按任意键重新输入\n" : text;
}
std::cout << text;
_getch();
} while (true);
}