ifstream与fread的二进制文件(ifstream vs. fread for binary files)

 哪个更快？ ifstream或fread 。 
 我应该用哪个来读取二进制文件？ 
 
 fread()将整个文件放入内存中。 
 所以在fread之后，访问它创建的缓冲区很快。 
 
 ifstream::open()是否将整个文件放入内存？ 
 或者每次运行ifstream::read()时它是否访问硬盘？ 
 
 那么...... ifstream::open() == fread()吗？ 
 或（ ifstream::open(); ifstream::read(file_length); ）== fread() ？ 
 
 或者我应该使用ifstream::rdbuf()->read() ？ 
 
 编辑：我的readFile（）方法现在看起来像这样： 
 
void readFile()
{
    std::ifstream fin;
    fin.open("largefile.dat", ifstream::binary | ifstream::in);
    // in each of these small read methods, there are at least 1 fin.read()
    // call inside.
    readHeaderInfo(fin);
    readPreference(fin);
    readMainContent(fin);
    readVolumeData(fin);
    readTextureData(fin);
    fin.close();
}
 
 使用小方法的多个fin.read（）调用会减慢程序吗？ 我只能在main方法中使用1个fin.read（）并将缓冲区传递给小方法吗？ 我想我打算写一个小程序进行测试。 
 
 谢谢！ 

Which is faster? ifstream or fread.
 Which should I use to read binary files? 
 
fread() puts the whole file into the memory.
 So after fread, accessing the buffer it creates is fast.
 
Does ifstream::open() puts the whole file into the memory?
 or does it access the hard disk every time we run ifstream::read()?
 
So... does ifstream::open() == fread()?
 or (ifstream::open(); ifstream::read(file_length);) == fread()?
 
Or shall I use ifstream::rdbuf()->read()?
 
edit: My readFile() method now looks something like this:
 
void readFile()
{
    std::ifstream fin;
    fin.open("largefile.dat", ifstream::binary | ifstream::in);
    // in each of these small read methods, there are at least 1 fin.read()
    // call inside.
    readHeaderInfo(fin);
    readPreference(fin);
    readMainContent(fin);
    readVolumeData(fin);
    readTextureData(fin);
    fin.close();
}
 
Will the multiple fin.read() calls in the small methods slow down the program? Shall I only use 1 fin.read() in the main method and pass the buffer into the small methods? I guess I am going to write a small program to test.
 
Thanks!

原文：https://stackoverflow.com/questions/6131307