Expression Handling

/* To covert an Infix Expression into Postfix */
#include <stdio.h>
#include <conio.h>
#include <process.h>

/*------------------------- Stack -----------------------------------------------------------*/

#define MaxSize 20
int Top=-1;
char opstk[MaxSize];

void Push (char op)
{
opstk[++Top] = op;
}

char Pop ()
{
return(opstk[Top--]);
}

int IsEmpty ()
{
return (Top==-1);
}

/*------------------------- End Of Stack ------------------------------------------------------*/

int IsOperand(char ch)
{
return ( ch>='A' && ch<='Z' || ch>='a' && ch<='z' );
}

int PrcdVal (char op)
{
switch(op)
{
case '^' : return (1);
case '*' :
case '/' : return (2);
case '+' :
case '-' : return (3);
default : printf ("Invalid Operator.\n");
return (0);
}
}

int Prcd (char op1, char op2)
{
int r1, r2;

if (op1=='(')
return(0);

if ( op2=='(' && op1!=')')
return(0);

if ( op2==')' && op1!='(')
return(1);