Computing a String

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.

Code:

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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 ) ;
  }
}

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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

Yup! Priority is needed.

Quote:

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Originally Posted by everard

Yup! Priority is needed.

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Guess who's job is thathttp://img.photobucket.com/albums/v6...ion/1ptgno.gif

Quote:

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Originally Posted by 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.

---

Do your own homework

Quote:

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Originally Posted by 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.

---

Your signature is ironic.

Quote:

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Originally Posted by penagate

Your signature is ironic.

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:lol: I almost said something about that in my post.

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

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

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...

Quote:

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Originally Posted by 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...

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