Postfix Program Using Stack

#define MAX 10

class stack

{

int a[MAX];

int x;

int top;

public:

stack()

{x=0;

top=-1;}

int push(int );

int pop();

int peek();

int empty();

};

int stack::push(int d)

{
if(top==MAX-1)

{
return 0;
}

else

{
top++;

a[top]=d;

return a[top];

} 
}

int stack::pop()

{
int x;

if(top==-1)

{
return 0;}

else

{
x=a[top];

top--;

return x;

} 
}

int stack::peek()

{
int x;

if(top==-1)

{return 0;}

else

{
x=a[top];

return x;

}  
}

int stack::empty()

{
int x;

if(top==-1)

{
return 1;}

else

{
return 0;

} 
}

void main()

{

stack o;

clrscr();

int k,l,p=0,q=0,x,y,z;

char s[30];

cin>>s;

l=strlen(s);

cout<<l;

for(int i=0;i<l;i++)

{
if(isdigit(s[i]))

{
k=s[i]-48;

p=o.push(k);

cout<<"\n\t"<<p;}

else

{
cout<<i<<s[i];

switch(s[i])

{
case '+':

x=o.pop();

y=o.pop();

z=x+y;

q=o.push(z);

cout<<"\n\tpush="<<q;

break;

case '-':

x=o.pop();

y=o.pop();

z=y-x;

q=o.push(z);

cout<<"\n\tpush="<<q;

break;

case '*':

x=o.pop();

y=o.pop();

z=x*y;

q=o.push(z);

cout<<"\n\tpush="<<q;

break;
}
}
}

q=o.pop();

cout<<"result"<<q;

getch();

}