redirecting input in c++

i was told that to redirect from standard input to file i need to do the following:

static std::ifstream inF("inpur.txt");
std:开发者_JS百科:cin.rdbuf(inF.rdbuf());

and every call to std::cin will be redirected to input.txt. but my question is: do i need to open inF? and if i do, where do i need to do this?

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You opened it by calling it with the string constructor.

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That's the beauty. You already did so while declaring the object and passing the string to the explicit constructor of ifstream.

The file is opened in TEXT mode.

Refer this

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Your code as-is fine. Do make a backup though of the original cin.rdbuf -- you may need to reset it in case of an error.