c++ map insert
To insert elements into a map in C++, you can use the insert
function. Here are the steps involved:
Create a map variable: Start by defining a map variable to store key-value pairs. For example, you can declare a map of integers to strings like this:
std::map<int, std::string> myMap;
Create a pair: To insert a new element into the map, you need to create a pair of values. The first value represents the key, and the second value represents the corresponding value. For example, you can create a pair like this:
std::pair<int, std::string> myPair(1, "Hello");
Use the insert function: To insert the pair into the map, you can call the
insert
function on the map variable. Pass the pair as an argument to theinsert
function. For example, you can insert the pair into the map like this:myMap.insert(myPair);
Insert using make_pair: An alternative way to insert elements into a map is by using the
make_pair
function. This function creates a pair using the provided values. For example, you can insert a pair usingmake_pair
like this:myMap.insert(std::make_pair(2, "World"));
Insert using initializer list: C++11 introduced another way to insert elements into a map using an initializer list. You can pass a list of pairs to the
insert
function. For example, you can insert multiple elements into the map like this:myMap.insert({{3, "Foo"}, {4, "Bar"}});
Check the result: After inserting elements into the map, you can check if the insertion was successful. The
insert
function returns a pair of an iterator to the newly inserted element and a boolean value indicating whether the insertion was successful or not. For example, you can check the result like this:auto result = myMap.insert(std::make_pair(5, "Baz"));
That's it! These are the steps involved in inserting elements into a map in C++. Remember to include the necessary headers (<map>
) at the beginning of your code to use the map container.