Computing a String

[everard]

Need Help...
How can I compute a string data type?
For example, the value of variable strInput is "1+2+3-4*5", and the answer must be -14.

Need reply ASAP! I know its very simple for you.

[ComputerJy]

import java.util.* ;

public class MyApp
{
  public static void main ( String args[] )
  {
    Scanner s = new Scanner( System.in ) ;
    System.out.println( "Please enter the mathematical expression" ) ;
    String expression = s.nextLine() ;
    Stack<Character> stNumbers = new Stack() ;
    Stack<Character> stOps = new Stack() ;
    for ( char c : expression.toCharArray() )
    {
      if ( Character.isDigit( c ) )
      {
	stNumbers.push( c ) ;
      }
      else
      {
	stOps.push( c ) ;
      }
    }
    double value = Double.parseDouble( stNumbers.pop().toString() ) ;
    while ( !stOps.isEmpty() )
    {
      double op2 = Double.parseDouble( stNumbers.pop().toString() ) ;
      switch ( stOps.pop().charValue() )
      {
	case '+':
	  value += op2 ;
	  break ;
	case '-':
	  op2 -= value ;
	  value = op2 ;
	  break ;
	case '*':
	  value *= op2 ;
	  break ;
	case '/':
	  op2 /= value ;
	  value = op2 ;
	  break ;
      }
    }
    System.out.println( "The value of the expression is " + value ) ;
  }
}

[ComputerJy]

That was a very simple algorithm I rapidly created. It doesn't prioritize division and multiplication over summation and subtraction, you need to work on it a little bit

[everard]

Yup! Priority is needed.

[ComputerJy]

Yup! Priority is needed.

Guess who's job is that

[System_Error]

Need Help...
How can I compute a string data type?
For example, the value of variable strInput is "1+2+3-4*5", and the answer must be -14.

Need reply ASAP! I know its very simple for you.

Do your own homework

[penagate]

Need Help...
How can I compute a string data type?
For example, the value of variable strInput is "1+2+3-4*5", and the answer must be -14.

Need reply ASAP! I know its very simple for you.

Your signature is ironic.

[System_Error]

Your signature is ironic.

I almost said something about that in my post.

[vagabon]

you would need to use a for loop to run through it to prioritize...

[CornedBee]

Huh? What's a for-loop got to do with an abstract parsing problem?

[vagabon]

I was stating that you would use a for loop to check for the order of operations
outer loop for addition
1 inner subtraction
2 inner for mulitiplication
3 inner for division
4th for exponets

There's a way to do the parathesises but it isn't hitting right now, another for loop that leads to a method to deal with them...

[ComputerJy]

I was stating that you would use a for loop to check for the order of operations
outer loop for addition
1 inner subtraction
2 inner for mulitiplication
3 inner for division
4th for exponets

There's a way to do the parathesises but it isn't hitting right now, another for loop that leads to a method to deal with them...

Yeah you are right, and I think it's a third Stack for parenthesis