Handling parenthesis while converting infix expressions to postfix expressions

Question

I\'m working on a project in Java that requires me to convert an infix expression to a postfix expression. I am currently able to convert infix expressions to postfix with t

Answer 1

You need to push the left parenthesis onto the stack, and process the stack like so when you encounter a right parenthesis:

// opening (
if (in_fix.peek().type == 4) {   
    post_fix.push(in_fix.pop());
}
//closing )
if(in_fix.peek().type == 5){
    while(!(post_fix.isEmpty() || post_fix.peek().type == 4)){
         postfixstr.append(post_fix.pop());
    }
    if (post_fix.isEmpty())
        ; // ERROR - unmatched )
    else
        post_fix.pop(); // pop the (
    in_fix.pop(); // pop the )
} 

Answer 2

Try this way:

    //opening Parenthesis 
        if (in_fix.peek().type == 4) {   
                    post_fix.push(in_fix.pop());
        }
        //closing Parenthesis 
        if(in_fix.peek().type == 5){
             //Till opening parenthesis encountered in stack, append operators to postfix. and pop parenthesis and do not append to post_fix.
             while(post_fix.peek().type!=4){
                 postfixstr.append(post_fix.pop());
             }
            //finally pop left parenthesis from post_fix stack.
            post_fix.pop();
        }