How to Effectively Reuse ostringstream Objects for Enhanced Buffer Management?

Reusing ostringstream Objects for Efficient Buffer Management

Background:
In C , ostringstream objects are commonly used for string manipulation tasks. However, continued usage of these objects can lead to performance inefficiencies due to repeated memory allocations.

Query:
To address this issue, developers may seek methods to clear and reuse ostringstream objects in order to reduce the need for allocations.

Solution:
To reset an ostringstream object to its initial state, utilize the following sequence:

<code class="cpp">s.clear();
s.str("");</code>

Alternative Approach:
If desired, manual clearing and retrieval of stream positions can be employed instead:

<code class="cpp">s.clear();
s.seekp(0); // For outputs: Set put pointer to beginning
s.seekg(0); // For inputs: Set get pointer to beginning</code>

Benefits:
This approach prevents unnecessary reallocations by overwriting existing buffer content instead of creating a new one.

Example:
Consider the following code:

<code class="cpp">std::ostringstream s;
s << "hello";
s.seekp(0);
s << "b";
assert(s.str() == "bello");</code>

Additional Note:
To make the string compatible with C-style functions that require null terminators, use std::ends:

<code class="cpp">std::ostringstream s;
s << "hello";
s.seekp(0);
s << "b" << std::ends;
assert(s.str().size() == 5 && std::strlen(s.str().data()) == 1);</code>

This is a remnant of the outdated std::strstream, but it remains useful for situations such as the example above.

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