#include <iostream>
#include <cstring>
#include <cmath>
#include <stack>
#include <iomanip>
#include <cstdlib>
#include <complex>
#include <complex.h>
using namespace std;
stack<char> opt; //操作符栈
stack<double> val; //操作数栈
//求阶乘所用数组
int LargeNumberFactorial[1000] = { 0 };
//定义两个常量表示在数字中的状态
const int IN = 0;
const int OUT = 1;
char opt_set[10] = "+-*/()=.";
int level(char theOpt); //操作符的优先级
bool in_set(char theChar); //判断输入的操作符是否合法，仅包括()+-*/
bool del_space(string &theString); //用于去除空格并检查是否有非法字符
string to_string(int theInt); //把数字转换成字符串
bool change(string &from, string &to); //将中缀表达式转换成后缀表达式
bool compute(string &theExp); //计算后缀表达式
int Judge_rectangle(string& theStr); //判断是否为三角函数或反三角函数并返回对应的编号
double cal_rect_number(string& theStr, int theInt); //求三角函数里包含的数字并求出对应的结果
bool Judge_factorial(string& theStr); //判断是否为求阶乘
int cal_factorial(int theInt); //利用数组求阶乘
int cal_factorial_number(string& theStr); // 求阶乘所求的数字
int main()
{
cout << "欢迎使用计算器" << endl;
cout << "你可以使用这个计算器做一些简单的运算" << endl;
cout << "如果你想退出，输入:exit即可..." << endl;
while (true) {
//输入表达式
string init_exp;
cout << "---请输入表达式:";
cin >> init_exp;
//判断是否要退出
if (init_exp == string("exit")) {
cout << "感谢您的使用..." << endl;
break;
}
//判断是否三角函数和反三角函数并求值
else if(Judge_rectangle(init_exp) != 0) {
double res = 0;
res = cal_rect_number(init_exp, Judge_rectangle(init_exp));
if (res)
cout << "结果为: " << fixed << setprecision(9) << res << endl;
}
//求阶乘的情况
else if (Judge_factorial(init_exp)) {
int n = cal_factorial_number(init_exp);
cout << "结果为: ";
for (int i = cal_factorial(n); i > 0; i--)
cout << LargeNumberFactorial[i];
cout << endl;
}
//是加减乘除的情况
else{
cin.clear();
cin.sync();
while (!opt.empty()) {
opt.pop();
}
while (!val.empty()) {
val.pop();
}
del_space(init_exp);//去除空格
string cng_exp;
cng_exp.clear();
change(init_exp, cng_exp); //转换为后缀表达式
compute(cng_exp);//计算后缀表达式
double stdans = val.top();
cout << "结果为:" << (double)stdans << endl;
}
}
return 0;
}
/*为每一个操作符返回一个数，数代表了优先级*/
int level(char theOpt)
{
switch (theOpt) {
case '(':
return 0;
case '+':
case '-':
return 1;
case '*':
case '/':
return 2;
case ')':
return 3;
}
}
/*判断输入的操作符是否合法*/
bool in_set(char theChar) {
for (int i = 0; i < 8; i++) {
if (theChar == opt_set[i])
return true;
}
return false;
}
/*用于去除空格并检查是否有非法字符*/
bool del_space(string& theString)
{
string res;
for (int i = 0; i < theString.length(); i++) {
if (in_set(theString[i]) || isdigit(theString[i]))
res += theString[i];
else if (theString[i] == ' ') {}
else{
cout << "The enter is Wrong" << endl;
return false;
}
}
theString = res;
return true;
}
/*把数字转换成字符串*/
string to_string(int theInt)
{
if (theInt == 0)
return string("0");
bool neg = false;
if (theInt < 0)
{
neg = true;
theInt = -theInt;
}
string res;
while (theInt != 0)
{
char c = (theInt % 10) + '0';
res = c + res;
theInt /= 10;
}
if (neg)
res = '-' + res;
return res;
}
/*将中缀表达式转换成后缀表达式*/
bool change(string &from, string &to)
{
int theInt = 0;
int state = OUT;
char c;
for (int i = 0; i < from.length(); i++)
{
c = from[i];
if (isdigit(c)) {
to = to + c;
theInt *= 10;
theInt += c - '0';
state = IN; //状态改为在数字内
}
else{
if (state == IN && c == '.') {
to = to + '.';
theInt = 0;
continue;
}
if (state == IN && c != '.') {
to += ' ';
theInt = 0;
}
if (c == '=')
break;
else if (c == '(')
opt.push(c);
else if (c == ')') {
while (!opt.empty() && opt.top() != '(') {
to += opt.top();
to += ' ';
opt.pop();
}
opt.pop();
}
else {
while (true) {
if (opt.empty() || opt.top() == '(')
opt.push(c);
else if (level(c) > level(opt.top()))
opt.push(c);
else {
to += opt.top();
to += ' ';
opt.pop();
continue;
}
break;
}
}
state = OUT; //状态为在数字外
}
}
while (!opt.empty()) {
to += opt.top();
to += ' ';
opt.pop();
}
return true;
}
/*计算后缀表达式*/
bool compute(string &theExp)
{
int theInt = 0; //暂存数字
int state = OUT;//初始状态为在数字外
char c;
bool dot = false;
double count = 1.0;
for (int i = 0; i < theExp.length(); i++)
{
c = theExp[i];
if (isdigit(c)|| c == '.') {
if (isdigit(c)) {
theInt *= 10;
theInt += c - '0';
state = IN; //状态为在数字内
if (dot == true)
count *= 10.0;
}
if (c == '.') {
dot = true;
continue;
}
}
else{
dot = false;
double ans = theInt / count;
count = 1.0;
if (state == IN) {
val.push(ans);
theInt = 0;
}
double x, y;
if (c != ' ') {
x = val.top();val.pop();
y = val.top();val.pop();
switch (c) {
case '+':val.push(x + y); break;
case '-':val.push(y - x); break;
case '*':val.push(x * y); break;
case '/':val.push(y / x); break;
default:cout << "未知的错误!" << endl;
}
}
state = OUT;
}
}
return true;
}
/*判断是否为三角函数或反三角函数并求出里面的数值*/
int Judge_rectangle(string& theStr)
{
string str1 = "sin";
string str2 = "cos";
string str3 = "tan";
string str4 = "arcsin";
string str5 = "arccos";
string str6 = "arctan";
const char* show1, *show2, *show3, *show4, *show5, *show6;
show4 = strstr(theStr.c_str(), str4.c_str());
if (show4 != NULL)
return 4;
show5 = strstr(theStr.c_str(), str5.c_str());
if (show5 != NULL)
return 5;
show6 = strstr(theStr.c_str(), str6.c_str());
if (show6 != NULL)
return 6;
show1 = strstr(theStr.c_str(), str1.c_str());
if (show1 != NULL)
return 1;
show2 = strstr(theStr.c_str(), str2.c_str());
if (show2 != NULL)
return 2;
show3 = strstr(theStr.c_str(), str3.c_str());
if (show3 != NULL)
return 3;
return 0;
}
/*求三角函数里包含的数字并求出对应的结果*/
double cal_rect_number(string& theStr, int theInt)
{
int number = 0;
for (int i = 0; theStr[i] != ')'; i++)
{
if (isdigit(theStr[i])) {
number *= 10;
number += theStr[i] - '0';
}
}
double ans = 0.0;
switch (theInt)
{
case 1:ans = sin(number); break;
case 2:ans = cos(number); break;
case 3:ans = tan(number); break;
case 4:ans = asin(number); break;
case 5:ans = acos(number); break;
case 6:ans = atan(number); break;
default:return 0;
break;
}
return ans;
}
/*判断是否为求阶乘*/
bool Judge_factorial(string& theStr)
{
int len = theStr.length();
for (int i = 0; i < len; i++)
if (theStr[i] == '!')
return true;
return false;
}
/*求阶乘所求的数字*/
int cal_factorial_number(string& theStr)
{
int number = 0;
for (int i = 0; theStr[i] != '!'; i++)
{
if (isdigit(theStr[i])) {
number *= 10;
number += theStr[i] - '0';
}
}
return number;
}
/*利用数组求阶乘*/
int cal_factorial(int theInt)
{
LargeNumberFactorial[0] = 1;
LargeNumberFactorial[1] = 1;
int digit = 1;
for (int i = 1; i <= theInt; i++)
{
for (int j = 1; j <= digit; j++)
{
LargeNumberFactorial[j] *= i;
}
for (int j = 1; j <= digit; j++)
{
if (LargeNumberFactorial[j] > 10)
{
for (int k = 1; k <= digit; k++)
{
if (LargeNumberFactorial[digit] > 9)
digit++;
LargeNumberFactorial[k + 1] += LargeNumberFactorial[k] / 10;
LargeNumberFactorial[k] %= 10;
}
}
}
}
return digit;
}