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Difference between revisions of "Template:cpp/container/empty ad"

From cppreference.com
m (fmt.)
m (→‎Example: simplified.)
 
Line 1: Line 1:
−
{{#vardefine:cont|{{{1|stack}}}}}<!--
+
{{#vardefine:cont|{{{1|priority_queue}}}}}<!--
 
-->{{cpp/container/{{#var:cont}}/title|empty}}
 
-->{{cpp/container/{{#var:cont}}/title|empty}}
 
{{cpp/container/{{#var:cont}}/navbar}}
 
{{cpp/container/{{#var:cont}}/navbar}}
Line 44: Line 44:
 
{{example
 
{{example
 
|code=
 
|code=
−
#include <iostream>
+
#include <cassert>
 
#include <{{#var:id}}>
 
#include <{{#var:id}}>
  
 
int main()
 
int main()
 
{
 
{
−
    std::cout << std::boolalpha;
 
−
 
 
     std::{{#var:cont}}<int> {{#var:id}};
 
     std::{{#var:cont}}<int> {{#var:id}};
 +
    assert({{#var:id}}.empty());
  
−
     std::cout << "Initially, {{#var:id}}.empty(): " << {{#var:id}}.empty() << '\n';
+
     {{#var:id}}.push(42);
 +
    assert(!{{#var:id}}.empty());
  
−
     {{#var:id}}.push(42);
+
     {{#var:id}}.pop();
−
     std::cout << "After adding elements, {{#var:id}}.empty(): " << {{#var:id}}.empty() << '\n';
+
     assert({{#var:id}}.empty());
 
}
 
}
−
|output=
 
−
Initially, {{#var:id}}.empty(): true
 
−
After adding elements, {{#var:id}}.empty(): false
 
 
}}
 
}}
 
}}
 
}}

Latest revision as of 21:23, 1 November 2024

 
C++
 
Containers library
 
std::priority_queue
 
bool empty() const;

Checks if the underlying container has no elements. Equivalent to: return c.empty().

Contents

[edit] Parameters

(none)

[edit] Return value

true if the underlying container is empty, false otherwise.

[edit] Complexity

Constant.

[edit] Example

Run this code
#include <cassert>
#include <queue>
 
int main()
{
    std::priority_queue<int> queue;
    assert(queue.empty());
 
    queue.push(42);
    assert(!queue.empty());
 
    queue.pop();
    assert(queue.empty());
}

[edit] See also

 returns the number of elements
(public member function of std::priority_queue<T,Container,Compare>) [edit]
(C++17)
 checks whether the container is empty
(function template) [edit]
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