Comparison operators allow us to compare two values against one another. A comparison returns a boolean result of either true or false. The table below lists each of the comparison operators and their usages:
|>=||Greater Than Or Equal To|
|<=||Less Than Or Equal To|
|!=||Not Equal To|
A Basic Comparison
In the following example, we compare two variables
y. We store the result of this comparison in variable
var x = 10; var y = 8; var z = x > y; println(z);
What will get printed to the screen? The above comparison, x > y, is evaluating if 10 is greater than 8. Because 10 is indeed greater than 8,
z is assigned a value of true. Thus,
true will get printed to the screen.
Let's get a little more practice. Take a look at the following code segment below. Pay close attention to each comparison and the operator being used.
var a = 3; var b = 5; var c = 2; var d = 3; var t = a > 0; var u = a == d; var v = d >= b; var w = b > c; var x = a != d; var y = d < = a; var z = 4 < = c;
println("t = " + t); println("u = " + u); println("v = " + v); println("w = " + w); println("x = " + x); println("y = " + y); println("z = " + z);
When we run this code, what boolean values (true or false) will get printed to the screen for variables t through z? See if you can figure it out on your own. The solution is given below.
t = true u = true v = false w = true x = false y = true z = false
Comparison Operators in a Program
Suppose we want to write a program which restricts people under a certain height from riding on a roller coaster. For this particular roller coaster, people who are under 4 feet (48 inches) are not allowed on the ride. How would we do this?
var height = readInt("How tall are you (in inches)? "); var isTallEnough = height >= 48; println("Can ride on the roller coaster: " + isTallEnough);
A common mistake is using
= when you actually want to use
= is used for assignment of variables whereas
== is used for comparing the equality of two values.
x = 5 stores the value
5 into the variable
x == 5 tests to see if the value
5 is equal to the variable
x and then returns either true or false. They are not the same thing!