Infix to Postfix Conversion

 

#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>
#define MAXSIZE 20

void push(char x);
char pop();
int priority(char ch);
int stack[MAXSIZE];
int top=-1;

void main()
{

    char exp[15],ch;
    int i=0;
    printf("enter the expresion: ");
    gets(exp);
    while(exp[i]!='\0')
    {
        if(isalnum(exp[i]))
        {
            putchar(exp[i]);
        }
        else if(exp[i]==')')
        {
            while(stack[top]!='(')
            {
                putchar(pop());
            }
            ch=pop();

        }
        else  if(exp[i]=='(')
        {
            push('(');
        }
        else
        {

            while(priority(stack[top])>=priority(exp[i]))
            {

                putchar(pop());
            }
            push(exp[i]);
        }
        i++ ;
    }


    while(top!=-1)
    {

        putchar(pop());

    }

}

void push(char x)
{
    if(top==MAXSIZE-1)
    {
        printf("STACK IS FULL");
        exit(1);

    }
    else
    {
        top++;
        stack[top]=x;
    }
}

char pop()
{
    char x;


    if(top==-1)
        exit(1);
    else
    {   x=stack[top];
        top--;
        return x;
    }

}


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


}

     

           

Note: Need to be arranged in compiler after copied

   

 OutPut:

enter the expresion: (a+b)*(c+d) ab+cd+*