Relational operators compare two values and then return a Boolean value (true
or false
, as described in Chapter 3). The greater than operator (>
), for example, returns true
if the value on the left of the operator is greater than the value on the right. Thus, 5>2
returns the value true
, whereas 2>5
returns the value false
.
The relational operators for C# are shown in Table 4-1. This table assumes two variables: bigValue
and smallValue
, in which bigValue
has been assigned the value 100, and smallValue
the value 50.
Table 4-1. C# relational operators (assumes bigValue = 100 and smallValue = 50)
Name | Operator | Given this statement | The expression evaluates to |
---|---|---|---|
Equals |
|
|
|
Not equals |
|
|
|
Greater than |
|
|
|
Greater than or equal to |
|
|
|
Less than |
|
|
|
Less than or equal to |
|
|
|
Each of these relational operators acts as you might expect. Notice that most of these operators are composed of two characters. For example, the “greater than or equal to” operator (>=
) is made up of the greater-than symbol (>
) and the equals sign (=
). The symbols must appear in that order for the operator to be valid; =<
isn’t a valid operator, and =>
is a different operator altogether, but one you won’t see until much later in the book.
Notice also that the equals operator is made up of two equals signs (==
) because the single equals sign alone (=
) is reserved for the assignment operator.
A very common beginner mistake is to confuse the assignment operator (=
) with the equals operator (==
). Even experienced programmers do this from time to time. Just remember that the latter has two equals signs, and the former only one.
The C# equals operator (==
) tests for equality between the objects on either side of the operator. This operator evaluates to a Boolean value (true
or false
). Thus, the statement:
myX == 5;
evaluates to true
if and only if the myX
variable has a value of 5.