Infix Expression to Post-fix (Reverse police) Notation

Here we just look out the code on Infix to Postfix expression notation.

It is also known as Reverse police method.

Find the full code snippet below.

Sample Code of Reverse Police Method

```/* Infix expression to post-fix (Reverse police) notation RabinsXp.com */
#include<stdio.h>
#include<ctype.h>
#define MAX 100
typedef struct stack { int data[MAX]; int top;}stack;

int priority(char x)
{
if(x == '(')  return(0);
if(x == '+' || x == '-')  return(1);
if(x == '*' || x == '/' || x == '%')  return(2);
if(x == '^') return (3);
return(4);
}

void init(stack *s){   s->top=-1;}
int empty(stack *s){ if(s->top==-1) return(1);  else return(0);}
int full(stack *s){ if(s->top==MAX-1) return(1); else return(0);}
void push(stack *s,char x){ s->top=s->top+1;  s->data[s->top]=x;}
char pop(stack *s){ int x=s->data[s->top]; s->top=s->top-1;  return(x); }
char top(stack * s){  return(s->data[s->top]);}

main()
{
stack s; char x; int token; init(&s);
printf("nEnter infix expression:");
while((token=getchar())!='\n')
{
if(isalnum(token)) printf("%c",token);
else
if(token == '(') push(&s,'(');
else
{
if(token == ')')
while((x=pop(&s))!='(')
printf("%c",x);
else
{
while(priority(token)<=priority(top(&s)) && !empty(&s))
{
x=pop(&s); printf("%c",x);
}
push(&s,token);
}
}
}
while(!empty(&s))
{
x=pop(&s); printf("%c",x);
}
return (0);
}
```

Rabins Sharma Lamichhane

Rabins Sharma Lamichhane is the owner of RabinsXP who is constantly working for increasing the Internet of Things (IoT) in Nepal. He also builds android apps and crafts beautiful websites. He is also working with various social services. The main aim of Lamichhane is to digitally empower the citizens of Nepal and make the world spiritually sound better both in terms of technology and personal development. Rabins is also the first initiator of Digital Nepal.