What is output by the code below?

Question

 

public static void withdraw(double balance, double amount)

{

  balance -= amount;

}

 

///////////////////////////////////////////////////////////////////////////////////////

//client code in the main of a runner class

double balance = 1020.37;

double amount = 350;

withdraw(balance, amount);        

System.out.println(balance);

Answer 1

Hi Bob,

The focal point of this question is around the assignment operator `-=`, let's break down the two parts of this operator.

The first part of the operator and the most simple assignment operator is `=`, this simply assigns a value to a given variable i.e. setting the balance variable to 1020.37. This just lets us be able to tell the computer to hold a certain value assigned to a name we choose to let us ask for it later.

The second part of this operator is the subtraction operator `-`. This is the same as what we usually reference as a subtraction sign, i.e. "5 - 3 = 2". In this question, it is exactly that as well. It lets us tell the computer we want to subtract a number.

Combining these together allows a "short hand" way to express an express less different to us.

`balance -= amount` is the same thing (equivalent to) `balance = balance - amount`

Try replacing the line `balance = balance - amount`.

Can you figure out the answer given this information?

Some resources to take a look at: https://www.tutorialspoint.com/java/java_basic_operators.htm, https://morioh.com/p/e5ec3d3cd3ff (some good examples of what the other link describes).