Trouble storing ifstream object in pair object

Hello, I am trying to store an ifstream in a pair object, but when I try to assign to pair_name.second (the ifstream object) an existing ifstream object, it fails with compiler errors hinting that the assignment operator of the ios::base type is private.

Any ideas what I can do to solve the problem?

Thanks.

Use a reference to an ifstream instead.

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Originally Posted by whiteflags

Use a reference to an ifstream instead.

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The problem is, the ifstream object I'm trying to assign to pair's object is a local object of a function, and so is the pair, and I'm adding the pair to a global vector. Why does it have to be a reference?

You can't copy C++ library stream objects.

Use a smart pointer with a null deleter or work on a different design that doesn't need a stream object.

Soma

Or, if the stream is guaranteed to exist for at least as long as the pair object, use a std::pair<whatever, ifstream *> and store a pointer to the stream.

That eliminates the need to copy the actual ifstream object around - which is not allowed, and is the cause of the compilation errors.

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Originally Posted by grumpy

Or, if the stream is guaranteed to exist for at least as long as the pair object, use a std::pair<whatever, ifstream *> and store a pointer to the stream.

That eliminates the need to copy the actual ifstream object around - which is not allowed, and is the cause of the compilation errors.

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Well, a pointer wouldn't work either, because I would be pointing at a local ifstream object in a function which is then destroyed after the function completes its execution, thus making it impossible to use that object in other functions, which is what I hoped to do, which is why I wanted to copy the object.
So I changed my design, and am no longer trying to hold on to the ifstream objects. I instead merely store the filenames of the files associated with those ifstream objects, along with the content of each file, so I can later open those files again in other functions using completely different ifstream objects, if I need to.

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Well, a pointer wouldn't work either, because I would be pointing at a local ifstream object in a function which is then destroyed after the function completes its execution

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But if you used a pointer, you wouldn't point it to a local object, but would instead create a heap object with new.

You could use new along with a std::unique_ptr. Remember to use appropriate std::move.