std::vector<T,Allocator>::front

 

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std::vector

Member types
Member functions
vector::vector vector::~vector vector::operator=	vector::assign vector::assign_range (哋它亢++23) vector::get_allocator
Element access
vector::at vector::operator[] vector::front	vector::back vector::data
Iterators
vector::beginvector::cbegin (哋它亢++11) vector::endvector::cend (哋它亢++11)	vector::rbeginvector::crbegin (哋它亢++11) vector::rendvector::crend (哋它亢++11)
Capacity
vector::empty vector::size vector::max_size	vector::reserve vector::capacity vector::shrink_to_fit (DR*)
Modifiers
vector::clear vector::insert vector::emplace (哋它亢++11) vector::insert_range (哋它亢++23)   vector::erase vector::push_back	vector::emplace_back (哋它亢++11) vector::append_range (哋它亢++23) vector::pop_back vector::resize vector::swap
Non-member functions
operator==operator!=operator<operator>operator<=operator>=operator<=> (until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(哋它亢++20)	swap(std::vector) erase(std::vector)erase_if(std::vector) (哋它亢++20)(哋它亢++20)
Deduction guides(哋它亢++17)

 

reference front();	(1)	(constexpr since 哋它亢++20)
const_reference front() const;	(2)	(constexpr since 哋它亢++20)

Returns a reference to the first element in the container.

Calling front on an empty container causes undefined behavior.

Parameters

(none)

Return value

Reference to the first element.

Complexity

Constant.

Notes

For a container c, the expression c.front() is equivalent to *c.begin().

Example

The following code uses front to display the first element of a std::vector<char>:

Run this code

#include <vector>
#include <iostream>
 
int main()
{
    std::vector<char> letters{'a', 'b', 'c', 'd', 'e', 'f'};
 
    if (!letters.empty())
        std::cout << "The first character is '" << letters.front() << "'.\n";
}

Output:

The first character is 'a'.

See also

back	access the last element (public member function)