1.5 Casting and Range of Variables

• 1 min read

Practice: predict the output (Java)

Write your answers, then check against the key below.
Q1

int a = 10, b = 4;
System.out.println(a / b);
System.out.println(a % b);
System.out.println((double)(a / b));
System.out.println((double)a / b);

2
2
2.0
2.5


Q2

double d = -2.6;
System.out.println((int)d);
System.out.println((int)(d - 0.5));
System.out.println((int)(-d + 0.5));

-2
-3
3


Q3

int x = Integer.MAX_VALUE;
int y = x + 2;
System.out.println(x);
System.out.println(y);

2147483647
-2147483647

FRQ - style tasks


FRQ 1 Average with correct casting Write a method avgInt that takes two int values and returns their average as a double, preserving the .5 if present.

public static double avgInt(int a, int b) {
    return (double) (a + b) / 2;
}
System.out.println(avgInt(3, 4))

3.5


FRQ 2 Given int correct and int total, compute the percentage as a double from 0.0 to 100.0 without losing fractional precision.

public static double percent(int correct, int total) {
    return (double) correct / total * 100.0;
}
System.out.println(percent(3, 5));

60.0


FRQ 3 Implement safeMod(int a, int b) that returns a % b, but if b == 0, it should return 0 instead of throwing.

public static int safeMod(int a, int b) {
    if (b == 0) {
        return 0;
    }
    return a % b;
}
System.out.println(safeMod(9, 29))

9