Detailed explanation of the usage of set in c++

set is a container that stores unique and ordered elements. The order of the elements is determined by the comparison function. Use the set syntax to create a set, insert elements using the insert() method, find elements using the find() method, and delete elements using the erase() method. The set can be traversed via an iterator or range-based for loop. Other useful methods include size(), empty(), clear(), lower_bound(), upper_bound(), and equal_range().

Detailed explanation of the usage of set in c

What is set?

set is a container that stores unique and ordered elements. The order of elements is determined based on a specific comparison function that determines the relative sizes of the elements.

Create a set

To create a set, you can use the following syntax:

<code class="cpp">set<T> mySet;</code>

Where, T is the element in the set type.

Insert elements

You can use the insert() method to insert elements into the set:

<code class="cpp">mySet.insert(element);</code>

If the element already exists, Insert operations will be ignored.

Find elements

You can use the find() method to find elements in the set:

<code class="cpp">auto it = mySet.find(element);</code>

If the element is found,it will point to the element; otherwise, it will point to the end of the set.

Delete elements

You can use the erase() method to delete elements in the set:

<code class="cpp">mySet.erase(it);</code>

Among them, it is an iterator pointing to elements. You can also use the erase() method to pass in the element value for deletion.

Traverse the set

You can use the following methods to traverse the elements in the set:

• Use an iterator:

<code class="cpp">for (auto it = mySet.begin(); it != mySet.end(); ++it) {
  // 获取元素
}</code>

• Use range-based for loop:

<code class="cpp">for (auto element : mySet) {
  // 获取元素
}</code>

Other methods of set

In addition to the above methods, set also provides the following useful methods:

• size(): Returns the number of elements in the set.
• empty(): Check whether set is empty.
• clear(): Clear all elements in the set.
• lower_bound(): Returns an iterator of the first element greater than or equal to the given element.
• upper_bound(): Returns an iterator of the first element greater than the given element.
• equal_range(): Returns a set of iterators representing the range of the given element in the set.

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