While（file_object）是导致无限循环的原因

Question

This seems rather strange. I have a snippet of code that is as follows:

List(const char* fn) {
    std::ifstream file(fn);

    if (!file){
        throw std::string("*** Failed to open file ") + std::string(fn) + std::string(" ***");
    }
    while (file) {
        T e;
        if (e.load(file)){
            list.push_back(*new T(e));
        }
    }
}

With other people, it seems to run through the whole file just fine. But for me, I'm stuck in an infinite loop on my machine.

OS X - g++ 4.2

I have no clue as to why there is a difference of function here.

Here is the infinite loop:

while (file) {
    T e;
    if (e.load(file)){
        list.push_back(*new T(e));
    }
}

Answer 1

while(file) will return true as long as the file is left in a valid state.

You haven't told us what a T is or what its load method does, so we can't really give you much more info than that. You need to make sure that the load method either closes the file descriptor, or leaves it in eof state or something else like that.