如何获得大于4 Gb的文件大小？

I made a simple function, which get's a file's size.

我做了一个简单的函数,它得到了文件的大小。

int file_size( char * filename )
{
     int size;
     struct stat st;

     stat( filename, &st );
     size = st.st_size;

     return size;

}//file_size

It is working fine, but if i have a file which size is bigger than 4Gb than i get a negativ number back, and of course this isn't the correct file size. So how can i get such a big file's size? I think, that the return value should anything else like int but i don't know what, and i don't think, that would solve my problem.

它工作正常,但如果我有一个大于4Gb的文件比我得到一个否定号码,当然这不是正确的文件大小。那我怎么能得到如此大的文件大小?我认为,返回值应该是其他任何像int但我不知道什么,我不认为,这将解决我的问题。

Thanks,

kampi

Update:

Hi!

I found the solution. I have to use __stat64. I modifyed my function, and now it is retrieving the real size. I tested it with an 8Gb big file.

我找到了解决方案。我必须使用__stat64。我修改了我的功能,现在它正在检索实际大小。我用8Gb大文件测试了它。

unsigned long long int file_size( char * filename )
{
    unsigned long long int size;
    struct __stat64 st;

    __stat64( filename, &st );
    size = st.st_size;

   return size;

}//file_size

And a notice:

并通知:

When i used printf, i had to use "%I64d" to print it out.

当我使用printf时,我不得不使用“%I64d”将其打印出来。

5 个解决方案

#1

You can probably use _stat64.

你可以使用_stat64。

#2

You can use the Win32 GetFileSizeEx function.

您可以使用Win32 GetFileSizeEx函数。

HANDLE aFile = CreateFile
(
  filename,
  FILE_READ_ATTRIBUTES,
  0,
  NULL,
  OPEN_EXISTING,
  FILE_ATTRIBUTE_NORMAL,
  NULL
);

if (aFile != INVALID_HANDLE_VALUE)
{
  long long aSize;
  GetFileSizeEx(aFile, &aSize);

  CloseHandle(aFile);
  return aSize;
}
else
  return -1;

#3

In such cases, return value of stat() might be -1, and errno set to EOVERFLOW.

在这种情况下,stat()的返回值可能为-1,而errno设置为EOVERFLOW。

The man page for stat on my (64 bit x86 machine) says:

我(64位x86机器)上stat的手册页说:

EOVERFLOW

(stat()) path refers to a file whose size cannot be represented in the type off_t. This can occur when an application compiled on a 32-bit platform without -D_FILE_OFFSET_BITS=64 calls stat() on a file whose size exceeds (2<<31)-1 bits.

(stat())path指的是无法在off_t类型中表示其大小的文件。在没有-D_FILE_OFFSET_BITS = 64的情况下在32位平台上编译的应用程序在大小超过(2 << 31)-1位的文件上调用stat()时,可能会发生这种情况。

#4

st_size is defined as long in wchar.h, so you could probably try with long, instead of int

st_size在wchar.h中定义为long,所以你可以尝试使用long,而不是int

struct stat {
    ....
    _off_t     st_size;
    ....
}

....

typedef long _off_t;

May be like this

可能是这样的

long file_size( char * filename )
{
     long size;
     struct stat st;

     stat( filename, &st );
     size = st.st_size;

     return size;

}//file_size

#5

I think , problem is because of file size more than INT_MAX , So that it is giving you negative values .

我认为,问题是因为文件大小超过INT_MAX,所以它给你负值。

Probably you can do type cast for long data type , it may work.

可能你可以为长数据类型进行类型转换,它可能会起作用。

Otherwise use , fseek , ftell function . then subtract end file pointer from start file pointer . It will also give you file size. ( number of bytes ) .

否则使用,fseek,ftell功能。然后从开始文件指针中减去结束文件指针。它还会为您提供文件大小。 (字节数)。

#1