c++ - 如何在 C++ 中读取一个空文件？

Question

如何在 C++ 中读取一个空文件？

我使用什么 while 循环条件来读取空文件？

因为 !fin.eof() 条件不起作用并创建无限循环。

我使用 Turbo C++，我有 2 个文件。音乐库文件中已有一些专辑。我需要过滤掉重复的专辑并将其添加到过滤器文件中。

我的代码如下:

void albumfilter()
{
    song s;
    album a;

    ifstream fin;
    fstream finout;

    fin.open("Musiclibrary.txt", ios::binary);

    while(!fin.eof())
    {
        fin.read((char*)&s,sizeof(s));
        if(fin.eof())
        break;

        finout.open("Filteralbum.txt", ios::binary| ios::in| ios::out);

        while(!finout.eof())
        {
            finout.read((char*)&a, sizeof(a));

            if(strcmp(a.getfilter_albumname(), s.getalbum())!=0)
            {
                strcpy(a.getfilter_albumname(),s.getalbum());
                 finout.write((char*)&a, sizeof(a));
                finout.close();
            }
        }
    }

    fin.close();
}

这段代码是否正确？

Answer 1

eof() 仅在尝试读取超过文件末尾时才会设置:您必须至少尝试读取一次。来自 std::basic_ios::eof :

This function only reports the stream state as set by the most recent I/O operation, it does not examine the associated data source. For example, if the most recent I/O was a get(), which returned the last byte of a file, eof() returns false. The next get() fails to read anything and sets the eofbit. Only then eof() returns true.