std::get_temporary_buffer in C++

In this article, you will learn about the std::get_temporary_buffer in C++ with its syntax and examples.

What is the std::get_temporary_buffer?

The <memory> header in C++ contains the std::get_temporary_buffer function, which is used to get a temporary buffer to hold uninitialized memory for a specific number of objects. When the temporary buffer is no longer required, this function is usually used in conjunction with the std::return_temporary_buffer function to release it.

Syntax:

It has the following syntax:

template <class T>
pair<T*,ptrdiff_t> get_temporary_buffer(ptrdiff_t n) noexcept;

Parameters:

n: The number of objects for which memory needs to be allocated.

Return Value:

std::pair<T*, ptrdiff_t>: It returns a pair containing a pointer to the beginning of the allocated memory block and the actual number of objects that can be stored in the allocated memory.

Exceptions:

It shouldn't raise any exceptions because the function is marked as noexcept. Nevertheless, some cases may still be exceptions because the implementation defines the behaviour.

Example 1:

Let's take an example to illustrate the use of the std::get_temporary_buffer in C++.

#include <memory>
#include <iostream>
int main() {
ptrdiff_t n = 5;
std::pair<int*, ptrdiff_t> buffer = std::get_temporary_buffer<int>(n);
if (buffer.second > 0) {
std::cout << "Successfully obtained a temporary buffer for " << buffer.second << " objects." << std::endl;
std::return_temporary_buffer(buffer.first);
} else {
std::cerr << "Failed to obtain a temporary buffer." << std::endl;
}
return 0;
}

Output:

Important Points:

The <memory> header in C++ contains the std::get_temporary_buffer function, which is used to get a temporary buffer to hold uninitialized memory for a specific number of objects. When the temporary buffer is no longer required, this function is usually used in conjunction with the std::return_temporary_buffer function to release it.
It shouldn't raise any exceptions because the function is marked as noexcept. Nevertheless, some cases may still be exceptions because the implementation defines the behaviour.

Remember that using std::get_temporary_buffer is comparatively low-level, and in contemporary C++, using higher-level abstractions like std::vector or smart pointers (std::unique_ptr or std::shared_ptr) is frequently advised to manage dynamic memory more conveniently and safely.

Benefits of std::get_temporary_buffer in C++:

The C++ Standard Library offers a function called std::get_temporary_buffer that lets you get a temporary buffer for dynamic memory allocation. This function is defined in the <memory_resource> header as of C++17 and is a <memory> header component.

The following are some advantages and applications for std::get_temporary_buffer:

Effective Memory Allocation: std::get temporary buffer is primarily used to allocate a temporary buffer efficiently for a given number of objects. It can be especially helpful when you require temporary storage for a computation or operation.
Resources for Custom Memory: Std::get_temporary_buffer can use custom memory resources as of C++17. This implies that by providing a custom allocator, you can use it with your memory management plan.
Preventing Memory Fragmentation: Utilizing a temporary buffer can prevent memory fragmentation in situations where many small allocations and deallocations are performed. It enables you to allocate a single, large block of memory, which has the potential to be more effective than several smaller allocations.
Exception Safety: A robust exception safety guarantee is built into the function. The function ensures that no resources are spilled and that the program stays in a consistent state if an exception is raised during allocation.
Optimized for Performance: Std::get_temporary_buffer may employ unique memory allocation techniques.

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