5.1.2 Pairs
A pair is exactly how it sounds, it is a pair of values. Pairs can be two values of the same type, but they can also contain values of a different type. Pairs are often used to hold two pieces of related data. You will see pairs used later as you explore key/value pairs with maps.
Creating Pairs
Pairs are part of the C++ standard library and do not need a special import statement.
To declare a pair, you use the keyword pair
and specify the two types of variables inside angled brackets and then the variable name.
Basic Form:
Examples:
When creating the pair, you can assign initial values by placing them inside curly brackets.
Examples:
Accessing and Updating Values
Accessing and updating values is similar to how values are accessed and updated with a struct. With structs, you access the value with a dot and the member name. Since a pair doesnโt have member variables, you simply access using the keywords first
and second
.
Example:
Output:
Updates are done using the same access.
Using Pairs
Just like any other data structure, pairs can be used as a separate data structure or as part of another data structure. In this example, you can see how pairs can be used with a vector or a queue.
Examples:
As mentioned above, pairs will be used for specific purposes in C++, like maps. Beyond that, pairs do have limited use since it can often be just as easy and more descriptive to create a struct. For example, if you wanted to store the first and last name, you can do this with a pair and then represent the first name in the first position and the last name in the second position.
Alternatively, you can create a name
struct and give the member names more descriptive values such as firstName
and lastName
.
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