# include <iostream.h>
 # include   <string.h>
 # include   <stdlib.h>
 # include    <conio.h>

 int top=-1;

 char Stack[100]={NULL};

 void push(constchar);
 constchar pop( );

 void infix_to_postfix(constchar *);


 int main( )
    {
       clrscr( );

       char Infix_expression[100]={NULL};

       cout<<"\n\n Enter the Infix Expression : ";
       cin.getline(Infix_expression,80);

       infix_to_postfix(Infix_expression);

       getch( );
       return 0;
    }


 /*************************************************************************///-----------------------------  push(const char)  ----------------------///*************************************************************************/void push(constchar Symbol)
    {
       if(top==99)
      cout<<"Error : Stack is full."<<endl;

       else
      {
         top++;
         Stack[top]=Symbol;
      }
    }

 /*************************************************************************///--------------------------------  pop( )  -----------------------------///*************************************************************************/constchar pop( )
    {
       char Symbol=NULL;

       if(top==-1)
      cout<<"Error : Stack is empty."<<endl;

       else
      {
         Symbol=Stack[top];
         Stack[top]=NULL;
         top--;
      }

       return Symbol;
    }

 /*************************************************************************///---------------------  infix_to_postfix(const char *)  ----------------///*************************************************************************/void infix_to_postfix(constchar *Infix)
    {
       char Infix_expression[100]={NULL};
       char Postfix_expression[100]={NULL};

       strcpy(Infix_expression,"(");
       strcat(Infix_expression,Infix);
       strcat(Infix_expression,")");

       char Symbol[5]={NULL};
       char Temp[5]={NULL};

       for(int count=0;count<strlen(Infix_expression);count++)
      {
         Symbol[0]=Infix_expression[count];

         if(Symbol[0]=='(')
        push(Symbol[0]);

         elseif(Symbol[0]==')')
        {
           Symbol[0]=pop( );

           while(Symbol[0]!='(')
              {
             strcat(Postfix_expression,Symbol);

             Symbol[0]=pop( );
              }
        }

         elseif(Symbol[0]=='^' || Symbol[0]=='*' || Symbol[0]=='/'
                    || Symbol[0]=='+' || Symbol[0]=='-')
        {
           if(Symbol[0]=='*' || Symbol[0]=='/')
              {
             Temp[0]=pop( );

             while(Temp[0]=='^' || Temp[0]=='*' || Temp[0]=='/')
                {
                   strcat(Postfix_expression,Temp);

                   Temp[0]=pop( );
                }

             push(Temp[0]);
              }

           elseif(Symbol[0]=='+' || Symbol[0]=='-')
              {
             Temp[0]=pop( );

             while(Temp[0]!='(')
                {
                   strcat(Postfix_expression,Temp);

                   Temp[0]=pop( );
                }

             push(Temp[0]);
              }

           push(Symbol[0]);
        }

         else
        strcat(Postfix_expression,Symbol);
      }

       cout<<"\n\n Postfix Expression : "<<Postfix_expression<<endl;
    }