C++ STL Set
Introduction to set
Sets are part of the C++ STL (Standard Template Library). Sets are the associative containers that stores sorted key, in which each key is unique and it can be inserted or deleted but cannot be altered.
Syntax
Parameter
T: Type of element stored in the container set.
Compare: A comparison class that takes two arguments of the same type bool and returns a value. This argument is optional and the binary predicate less<T>, is the default value.
Alloc: Type of the allocator object which is used to define the storage allocation model.
Member Functions
Below is the list of all member functions of set:
Constructor/Destructor
Iterators
Functions 
Description 
Begin 
Returns an iterator pointing to the first element in the set. 
cbegin 
Returns a const iterator pointing to the first element in the set. 
End 
Returns an iterator pointing to the pastend. 
Cend 
Returns a constant iterator pointing to the pastend. 
rbegin 
Returns a reverse iterator pointing to the end. 
Rend 
Returns a reverse iterator pointing to the beginning. 
crbegin 
Returns a constant reverse iterator pointing to the end. 
Crend 
Returns a constant reverse iterator pointing to the beginning. 
Capacity
Functions 
Description 
empty 
Returns true if set is empty. 
Size 
Returns the number of elements in the set. 
max_size 
Returns the maximum size of the set. 
Modifiers
Functions 
Description 
insert 
Insert element in the set. 
Erase 
Erase elements from the set. 
Swap 
Exchange the content of the set. 
Clear 
Delete all the elements of the set. 
emplace 
Construct and insert the new elements into the set. 
emplace_hint 
Construct and insert new elements into the set by hint. 
Observers
Functions 
Description 
key_comp 
Return a copy of key comparison object. 
value_comp 
Return a copy of value comparison object. 
Operations
Functions 
Description 
Find 
Search for an element with given key. 
count 
Gets the number of elements matching with given key. 
lower_bound 
Returns an iterator to lower bound. 
upper_bound 
Returns an iterator to upper bound. 
equal_range 
Returns the range of elements matches with given key. 
Allocator
Functions 
Description 
get_allocator 
Returns an allocator object that is used to construct the set. 
NonMember Overloaded Functions
Functions 
Description 
operator== 
Checks whether the two sets are equal or not. 
operator!= 
Checks whether the two sets are equal or not. 
operator< 
Checks whether the first set is less than other or not. 
operator<= 
Checks whether the first set is less than or equal to other or not. 
operator> 
Checks whether the first set is greater than other or not. 
operator>= 
Checks whether the first set is greater than equal to other or not. 
swap() 
Exchanges the element of two sets. 
