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× C++ Standard Library C++ STL Library

The C++ deque::max_size function is used to return the maximum size the deque can reach. The function returns the maximum potential size the deque can reach due to known system or library implementation limitations.


size_type max_size() const;
size_type max_size() const noexcept;


No parameter is required.

Return Value

Maximum number of elements that can be held in a deque.

Time Complexity

Constant i.e, Θ(1).


In the below example, the deque::max_size function is used find out the maximum number of elements that a deque can hold.

#include <iostream>
#include <deque>
using namespace std;
int main (){
  deque<int> MyDeque{10, 20, 30, 40, 50};
  deque<int>::iterator it;

  cout<<"The deque contains:";
  for(it = MyDeque.begin(); it != MyDeque.end(); ++it)
    cout<<" "<<*it;
  cout<<"\nDeque size is: "<<MyDeque.size()<<"\n";
  cout<<"Maximum size of the Deque: "<<MyDeque.max_size()<<"\n"; 
  return 0;

A possible output could be:

The deque contains: 10 20 30 40 50
Deque size is: 5
Maximum size of the Deque: 4611686018427387903

❮ C++ - Deque