chbaker0 chbaker0 - 3 months ago 10
C++ Question

Does std::string::clear reclaim the memory associated with a string?

For example, if loaded a text file into an std::string, did what I needed to do with it, then called clear() on it, would this release the memory that held the text? Or would I be better off just declaring it as a pointer, calling new when I need it, and deleting it when I'm done?

Answer

Calling std::string::clear() merely sets the size to zero. The capacity() won't change (nor will reserve()ing less memory than currently reserved change the capacity). If you want to reclaim the memory allocated for a string, you'll need to do something along the lines of

std::string(str).swap(str);

Copying the string str will generally only reserve a reasonable amount of memory and swapping it with str's representation will install the resulting representation into str. Obviously, if you want the string to be empty you could use

std::string().swap(str);
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