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

 

C++

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Symbols index

External libraries

 

Containers library

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array (C++11)

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unordered_set (C++11)

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span (C++20)

 

std::vector

Member functions

vector::vector

vector::~vector

vector::operator=

vector::assign

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Element access

vector::at

vector::operator[]

vector::front

vector::back

vector::data

Iterators

vector::beginvector::cbegin (C++11)

vector::endvector::cend (C++11)

vector::rbeginvector::crbegin (C++11)

vector::rendvector::crend (C++11)

Capacity

vector::empty

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vector::shrink_to_fit (C++11)

Modifiers

vector::clear

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vector::emplace_back (C++11)

vector::pop_back

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Non-member functions

std::swap

eraseerase_if (C++20)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides(C++17)

 

reference front();		(until C++20)
constexpr reference front();		(since C++20)
const_reference front() const;		(until C++20)
constexpr const_reference front() const;		(since C++20)

Returns a reference to the first element in the container.

Calling front on an empty container is undefined.

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 {'o', 'm', 'g', 'w', 't', 'f'};
 
    if (!letters.empty()) {
        std::cout << "The first character is '" << letters.front() << "'.\n";
    }  
}

Output:

The first character is 'o'.

See also

back	access the last element (public member function)