C++ std::list::max_size

The std::list::max_size function returns the maximum number of elements that the list container can hold. This value depends on the system or library implementation and is typically limited by the maximum value of the container’s allocator’s size_type.

Syntax of std::list::max_size

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size_type max_size() const noexcept;

Parameters

The std::list::max_size function does not take any parameters.

Return Value

Returns the maximum number of elements that the list container can theoretically hold, expressed as a value of type size_type. This value is an upper bound and is often much larger than practical memory constraints.

Exceptions

The std::list::max_size function does not throw exceptions as it is marked noexcept. It is a safe operation that provides an upper bound for the list’s capacity, as determined by the allocator’s limitations.

Examples for std::list::max_size

Example 1: Checking the Maximum Size of a List

This example demonstrates how to use the max_size() function to retrieve the maximum number of elements that a list can hold:

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#include <iostream>
#include <list>

int main() {
    std::list<int> myList;

    std::cout << "The maximum size of the list is: " << myList.max_size() << std::endl;

    return 0;
}

Explanation:

Define a list: A std::list named myList is created.
Get the maximum size: The max_size() function is called on myList to retrieve the maximum number of elements the list can hold. This value depends on the system or library implementation.
Print the maximum size: The result is printed to the console.

Output:

The maximum size of the list is: 384307168202282325

Note: The actual value may vary depending on your system and library implementation.

Example 2: Comparing Size and Max Size of a List

This example demonstrates how to compare the current size of a list with its maximum size:

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#include <iostream>
#include <list>

int main() {
    std::list<int> myList = {1, 2, 3};

    std::cout << "Current size of the list: " << myList.size() << std::endl;
    std::cout << "Maximum size of the list: " << myList.max_size() << std::endl;

    return 0;
}

Explanation:

Define a list: A std::list named myList is initialized with elements {1, 2, 3}.
Get the current size: The size() function is called to get the number of elements currently in the list.
Get the maximum size: The max_size() function is called to determine the maximum number of elements the list can theoretically hold.
Print the results: Both values are printed to the console.

Output:

Current size of the list: 3
Maximum size of the list: 384307168202282325

Note: The maximum size is usually much larger than the practical limit, which is constrained by available memory.

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C++ std::list::max_size