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Solution Review 2: Expression Evaluation

Solution Review 2: Expression Evaluation

Have a look at the solution to the 'Expression Evaluation' challenge.

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class ExpressionEvaluattion 
{
    public static void main(String args[]) 
    {
        int x = 2;                      // x = 2
        int y = 3;                      // y = 3,  x = 2
        double z = 5;                   // z = 5.0, y = 3, x = 2
        x *= y;                         // z = 5.0, y = 3, x = 2*3 = 6
        y = x + y + (int) z;            // z = 5.0, y = 6+3+5 = 14, x = 6
        z = x + y + y / z;              // z = 6+14+(14/5.0) = 22.8, y = 14, x = 6
        y++;                            // z = 22.8, y = 15, x = 6
        x--;                            // z = 22.8, y = 15, x = 5
        x = (int) z + y * x / y % x;    // x = 22 + ((15*5) / 15)) % 5 = 22 
        
        System.out.println(x);
    }
}

Explanation

Let’s go over the code line by line and keep track of each of the three variables.

  • In lines 5-7, we have three variables declared; variables x and y are of int type, whereas variable z is of double type.

  • Now, look at line 9. Remember that *= is shorthand for the arithmetic operation of multiplying the two numbers and assigning the resulting value to the variable on the left side of the *= sign. Thus, this line translates to:

    x = x * y;

    This way, the value of x is updated to 2Ă—3=62 \times 3 = 6.

  • Now, look at line 10. Here, the value of y is updated to the sum of the three variables we have. Since we cannot add variables of different types, variable z is being type casted to int. Otherwise, it is a simple sum, i.e., the value of y becomes 6+3+5=146+3+5=14 ...