Why should the explicitly assigned resources be immediately handed over to the resource management object in C++?
This article introduces the knowledge of why explicitly allocated resources are immediately handed over to resource management objects in C++. Many people will encounter this dilemma in the operation of actual cases. then let the editor lead you to learn how to deal with these situations! I hope you can read it carefully and be able to achieve something!
R.12: immediately hand over explicitly allocated resources to resource management objects
Reason (reason)
If you do not do so, a leak may occur when an exception occurs or when a return operation occurs.
Example, bad (negative example)
Void f (const string& name)
{
FILE* f = fopen (name, "r"); / / open the file
Vector buf (1024)
Auto _ = finally ([f] {fclose (f);}); / / remember to close the file
/ /...
}
Failure to allocate buffer (throw exception, translator's note) will cause the file handle to leak.
Example (sample)
Void f (const string& name)
{
Ifstream f {name}; / / open the file
Vector buf (1024)
/ /...
}
(managed with ifstream) the use of file handles is simple, efficient, and secure.
Enforcement (implementation recommendations)
Tag initializes pointers with explicitly allocated resources (the question is: how many cases can we identify when resources are allocated directly?)
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