Relational and equality operators ( ==, !=, >, <, >=, <= )
In order to evaluate a comparison between two expressions we can use the relational and equality operators. The
result of a relational operation is a Boolean value that can only be true or false, according to its Boolean result.
We may want to compare two expressions, for example, to know if they are equal or if one is greater than the
other is. Here is a list of the relational and equality operators that can be used in C++:
== Equal to
!= Not equal to
> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
Here there are some examples:
(7 == 5) // evaluates to false.
(5 > 4) // evaluates to true.
(3 != 2) // evaluates to true.
(6 >= 6) // evaluates to true.
(5 < 5) // evaluates to false.
Of course, instead of using only numeric constants, we can use any valid expression, including variables. Suppose
that a=2, b=3 and c=6,
(a == 5) // evaluates to false since a is not equal to 5.
(a*b >= c) // evaluates to true since (2*3 >= 6) is true.
(b+4 > a*c) // evaluates to false since (3+4 > 2*6) is false.
((b=2) == a) // evaluates to true.
Be careful! The operator = (one equal sign) is not the same as the operator == (two equal signs), the first one is an
assignment operator (assigns the value at its right to the variable at its left) and the other one (==) is the equality
operator that compares whether both expressions in the two sides of it are equal to each other. Thus, in the last
expression ((b=2) == a), we first assigned the value 2 to b and then we compared it to a, that also stores the
value 2, so the result of the operation is true.
In order to evaluate a comparison between two expressions we can use the relational and equality operators. The
result of a relational operation is a Boolean value that can only be true or false, according to its Boolean result.
We may want to compare two expressions, for example, to know if they are equal or if one is greater than the
other is. Here is a list of the relational and equality operators that can be used in C++:
== Equal to
!= Not equal to
> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
Here there are some examples:
(7 == 5) // evaluates to false.
(5 > 4) // evaluates to true.
(3 != 2) // evaluates to true.
(6 >= 6) // evaluates to true.
(5 < 5) // evaluates to false.
Of course, instead of using only numeric constants, we can use any valid expression, including variables. Suppose
that a=2, b=3 and c=6,
(a == 5) // evaluates to false since a is not equal to 5.
(a*b >= c) // evaluates to true since (2*3 >= 6) is true.
(b+4 > a*c) // evaluates to false since (3+4 > 2*6) is false.
((b=2) == a) // evaluates to true.
Be careful! The operator = (one equal sign) is not the same as the operator == (two equal signs), the first one is an
assignment operator (assigns the value at its right to the variable at its left) and the other one (==) is the equality
operator that compares whether both expressions in the two sides of it are equal to each other. Thus, in the last
expression ((b=2) == a), we first assigned the value 2 to b and then we compared it to a, that also stores the
value 2, so the result of the operation is true.