如何将ifstream转换为istream

Question

Is there any way I can convert an ifstream to an istream ? I have a function called getToken(istream* br) that accepts an istream as the parameter, but within my main() I use an ifstream to read a file, and I must use this same ifstream to call getToken . How can I overcome this issue?

Answer 1

As mentioned in the comments, you don't need to do anything fancy. The std::ifstream type inherits from std::istream , so any function that takes an istream* can take a pointer to an ifstream as input. For example:

string getToken(istream* stream) {
    ...
}

ifstream fileStream;
getToken(&fileStream);

The streams classes were specifically designed to make operations like this one possible.