c++中用栈编写计算器，为什么运行时只显示最后输入的那个数字？哪里出错了？

#include<iostream>
#include<string.h>
#include<cstdlib>
using namespace std;
#define Max 1000
struct s1
{
  float n[Max];
  int top;
}stack1 ;
struct s2
{
    char n[Max];
    int top;
}stack2;
int isempty(s1 s)
{
    if (s.top==-1)
        return 1;
    else
        return 0;
}
int isempty2(s2 s)
{
    if (s.top==-1)
        return 1;
    else
        return 0;
}
void push1(s1 &s,float x)
{
    if(s.top==Max-1)
    {
        cout<<"too much"<<endl;
        return;
    }
    s.top++;
    s.n[s.top]=x;
}
void push2(s2 &s,char x)
{
    if(s.top==Max-1)
    {
        cout<<"too much"<<endl;
        return;
    }
    s.top++;
    s.n[s.top]=x;
}
void pop1(s1 &s,float &e)
{
    if(s.top==-1)
    {
        cout<<"empty"<<endl;
        return;
    }
    e=s.n[s.top];
    s.top--;
}
void pop2(s2 &s,char &e)
{
   if(s.top==-1)
    {
        cout<<"empty"<<endl;
        return;
    }
    e=s.n[s.top];
    s.top--;
}
int in(char e)
{
    if(e=='+'||e=='-')
        return 2;
    else if(e=='*'||e=='/')
        return 4;
    else
    {
        cout<<"error"<<endl;
        return -1;

    }
}
int out(char e)
{
    if(e=='+'||e=='-')
        return 2;
    else if(e=='*'||e=='/')
        return 4;
    else
    {
        cout<<"error"<<endl;
        return -1;

    }
}
void count(float &x,char &e,float &y)
{
    float sum;
    if(e=='+')
        sum=x+y;
    if(e=='-')
        sum=x-y;
    if(e=='*')
        sum=x*y;
    if(e=='/')
        sum=x/y;
    push1(stack1,sum);
}
int main()
{
    long len,i=0,j,g;
    char line[Max],operate,temp[20];
    float a,b;
    cout<<"input the operation expression"<<endl;
    cin>>line;
    len=strlen(line);
    stack1.top=-1;
    stack2.top=-1;
    while(1)
    {
     g=0;
     if(isdigit(line[i]))
     {
        j=0,g=1;
        while(isdigit(line[i])||line[i]=='.')
            {
             temp[j++]=line[i];
             i++;
             if(i>=len)
                break;
            }
        temp[j]='\0';
        b=atof(temp);
        push1(stack1,b);
        i++;
        if(i>=len)
            break;
     }
     else
     {
        if(line[i]!='+'||line[i]!='-'||line[i]!='*'||line[i]!='/')
            cout<<"mistake in expression"<<endl;
        else{
            if(!isdigit(line[i+1]))
                cout<<"mistake in expression"<<endl;
            else
            {
                g=1;
                if(line[i]=='-'&&i==0)
                    {
                        push1(stack1,0);
                        push2(stack2,line[i]);
                    }
                else
                {
                    if(in(stack2.n[stack2.top])<out(line[i])||isempty2(stack2))
                       {
                           push2(stack2,line[i]);
                           i++;
                       }
                    else if(in(stack2.n[stack2.top])==out(line[i]))
                       {
                           i++;
                           push2(stack2,line[i]);
                       }
                    else
                        {
                            pop1(stack1,a);
                            pop1(stack1,b);
                            pop2(stack2,operate);
                            count(b,operate,a);
                        }
                }
            }
        }
     }
     while(stack2.top!=-1)
     {
         pop1(stack1,a);
         pop1(stack1,b);
         pop2(stack2,operate);
         count(b,operate,a);
     }
}
cout<<stack1.n[stack1.top]<<endl;
     return 0;
}