简单算术表达式计算器

#include<iostream>
#include<math.h>
#include<stdio.h>
#include<malloc.h>
#include<string.h>
#include<stdlib.h>
#define max 100
using namespace std;//push(i) pop() top() empty()
class a_stack
{
private:
double donser[max];
int length=0;
public:
void push_num(a_stack &l,double i);//入栈push
void pop_num(a_stack &l);//出栈pop
double top_num(a_stack &l);//返回栈顶数据top
int check_empty(a_stack &l);//检查是否为空empty
};
class b_stack
{
private:
char donser1[max];
int length1=0;
public:
void push_num(b_stack &l,char i);//入栈push
void pop_num(b_stack &l);//出栈pop
int top_num(b_stack &l);//返回栈顶数据top
int check_empty(b_stack &l);//检查是否为空empty
};

void a_stack::push_num(a_stack &l,double i)
{
int k;
l.length++;
k=l.length;
l.donser[k]=i;
}

void a_stack::pop_num(a_stack &l)
{
int k;
k=l.length;
l.length--;
l.donser[k]=0;
}

double a_stack::top_num(a_stack &l)
{
return l.donser[l.length];
}

int a_stack::check_empty(a_stack &l)//1为空
{
if(l.length==0){return 1;}
else return 0;
}

void b_stack::push_num(b_stack &l,char i)
{
int k;
l.length1++;
k=l.length1;
l.donser1[k]=i;
}

void b_stack::pop_num(b_stack &l)
{
int k;
k=l.length1;
l.length1--;
l.donser1[k]=0;
}

int b_stack::top_num(b_stack &l)
{
return l.donser1[l.length1];
}

int b_stack::check_empty(b_stack &l)//1为空
{
if(l.length1==0){return 1;}
else return 0;
}

int i;
double a,b;
char s[250],c;
int main()
{
cout<<"输入算式：";
while(gets(s),strcmp(s,"#")!=0)
{
//stack<char>s1;
//stack<double>s2;
b_stack s1;
a_stack s2;

for(i=0;s[i];i++)
{
if(s[i]>='0'&&s[i]<='9') //如果是数字继续找数字
{
a=0;
while(s[i]>='0'&&s[i]<='9')
{
a=a*10+s[i]-'0';
i++;
}
i--;
s2.push_num(s2,a);
}
else if(s[i]=='(') //如果(
{
s1.push_num(s1,s[i]);
}
else if(s[i]==')') //如果)
{
while(s1.top_num(s1)!='(')//找不到前括号就循环
{
c=s1.top_num(s1);//符号top
s1.pop_num(s1);//删掉
a=s2.top_num(s2);//数字top
s2.pop_num(s2);//删掉
b=s2.top_num(s2);//当前数字top
s2.pop_num(s2);//删掉
if(c=='+') a+=b;
if(c=='-') a=b-a;
if(c=='*') a=b*a;
if(c=='/') a=b/a;
s2.push_num(s2,a);
}
s1.pop_num(s1);//删除前括号
if(s1.check_empty(s1)==1){continue;}
if(s1.top_num(s1)=='*') //去掉括号以后栈还是乘
{
s1.pop_num(s1);//删掉
a=s2.top_num(s2);//数字top
s2.pop_num(s2);//删掉
b=s2.top_num(s2);//当前数字top
s2.pop_num(s2);//删掉
a=b*a;
s2.push_num(s2,a);
}
}
else if(s[i]=='-'||s[i]=='+') //如果是+-
{
if(s1.check_empty(s1)==0&&s1.top_num(s1)!='(')//优先级低或者一样交换符号
{
c=s1.top_num(s1);//字符栈顶
s1.pop_num(s1);//删掉
a=s2.top_num(s2);//数字栈顶1
s2.pop_num(s2);//删掉
b=s2.top_num(s2);//数字栈顶2
s2.pop_num(s2);//删掉
if(c=='+') a+=b;
if(c=='-') a=b-a;
if(c=='*') a=b*a;
if(c=='/') a=b/a;
s2.push_num(s2,a);//运算以后的入数字栈
s1.push_num(s1,s[i]);//字符入栈
}
else if(s1.check_empty(s1)==1||s1.top_num(s1)=='(')//如果空或者前括号
{
s1.push_num(s1,s[i]);//字符入栈
}
}
else if(s[i]=='/') //如果除
{
b=0;
c=s[i];//存一下符号
if(s1.check_empty(s1)==1||s1.top_num(s1)=='(') //空就入栈不运算
{
s1.push_num(s1,c);
continue;
}
i+=2;//找符号后面的数字
while(s[i]>='0'&&s[i]<='9')
{
b=b*10+s[i]-'0';
i++;
}
i--;//找到数字
a=s2.top_num(s2);//取出数字栈顶
s2.pop_num(s2);//删掉
if(s1.top_num(s1)=='*') //优先级一样交换符号
{
a=a*b;
s1.pop_num(s1);//删除原来的
s1.push_num(s1,c);//换成新的
}
else a=a/b;//优先级高做除法
s2.push_num(s2,a);//新数字入栈
}
else if(s[i]=='*') //如果乘
{
b=0;
c=s[i];
if(s1.check_empty(s1)==1||s1.top_num(s1)=='(')
{
s1.push_num(s1,c);
continue;
}
i+=2;
if(s[i]=='(')
{
s1.push_num(s1,c);
i--;
continue;
}
while(s[i]>='0'&&s[i]<='9')
{
b=b*10+s[i]-'0';
i++;
}
i--;
a=s2.top_num(s2);
s2.pop_num(s2);
if(s1.top_num(s1)=='/')
{
a=a/b;
s1.pop_num(s1);
s1.push_num(s1,c);
}
else if(s1.top_num(s1)!='/')
{
a=a*b;
}
s2.push_num(s2,a);
}

}
while(!s1.check_empty(s1))//如果符号栈非空就循环
{
c=s1.top_num(s1);//符号top
s1.pop_num(s1);//删掉
a=s2.top_num(s2);//数字top
s2.pop_num(s2);//删掉
b=s2.top_num(s2);//当前数字top
s2.pop_num(s2);//删掉
if(c=='+') a+=b;
if(c=='-') a=b-a;
if(c=='*') a=b*a;
if(c=='/') a=b/a;
s2.push_num(s2,a);
}
printf("%.2f\n",s2.top_num(s2));
}
return 0;
}