Binary Cipher
//Program for infix to postfix conversion
import java.util.*;
class itop1
{
char s[]=new char[10];
int top;
itop1() {top=-1; }
void i2post(char in[])
{
int i,j=0;
char post[]=new char[20];
char ichar,schar;
for(i=0;i<in.length;i++)
{
ichar=in[i];
if(isoperand(ichar)) post[j++]=ichar;
else
{
while(!isempty() && (val(ichar)<=val(topsmb())) && (ichar!='(‘))
{
schar=pop();
if(schar=='(‘) break;
if(ichar!='(‘) post[j++]=schar;
}
if(ichar!=’)’) push(ichar);
}
}
while(!isempty()) post[j++]=pop();
for(i=0;i<j;i++)
if((post[i]!='(‘) && (post[i]!=’)’))
System.out.print(post[i]);
}
boolean isoperand(char x)
{
return((x>=’0′ && x<=’9′) || (x>=’a’ && x<=’z’) || (x>=’A’ && x<=’Z’));
}
boolean isempty()
{
return (top==-1);
}
int val(char x)
{
switch(x)
{
case ‘)’ :
case ‘(‘ : return 0;
case ‘+’:
case ‘-‘ : return 1;
case ‘*’:
case ‘/’ : return 2;
case ‘$’: return 3;
default :System.out.println(“nInvalid expression !”+(char)7);
System.exit(1);
return 0;
}
}
char topsmb()
{
return (s[top]);
}
void push(char x)
{
top++;
s[top]=x;
}
char pop()
{
return (s[top–]);
}
}
class Itop
{
public static void main(String args[])
{
Scanner scr=new Scanner(System.in);
itop1 p=new itop1();
System.out.println(“nEnter infix expression : “);
String str=scr.next();
char b[]=str.toCharArray();
System.out.println(“nPost fix expression for “+str+” is :”);
p.i2post(b);
}
}
Output:
Enter infix expression :
(a+b)
Post fix expression for (a+b) is :
ab+