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Difference between revisions of "cpp/container/forward list/empty"

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Revision as of 20:11, 2 November 2012

[edit template]
 
C++
 
Containers library
 
std::forward_list
Member functions
Non-member functions
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides (C++17)
 
bool empty() const noexcept;
 (since C++11)

Checks if the container has no elements, i.e. whether begin() == end().

Contents

Parameters

(none)

Return value

true if the container is empty, false otherwise.

Complexity

Constant.

Example

[edit]

The following code uses empty to check if a std::forward_list<int> contains any elements:

Run this code
#include <forward_list>
#include <iostream>
 
int main()
{
    std::forward_list<int> numbers;
    std::cout << std::boolalpha;
    std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n';
 
    numbers.push_front(42);
    numbers.push_front(13317); 
    std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n';
}

Output: 

Initially, numbers.empty(): true
After adding elements, numbers.empty(): false

See also

 returns the distance between two iterators
(function template) [edit]
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