CODEWITHSUNDEEP
c++
user34537
user34537

Reputation:

File size of a >4gb file?

In MSVC I ran the following code. a gives me -1, b gives me EINVAL and c gives me 0. When the path is a file that can fit in a 32bit value this function works fine. How do I get the length of a file >4gb?

f = fopen(path.c_str(), "r+b");
printf("f=%X\n", f);
auto a = fseek(f, 0, SEEK_END);
auto b = errno;
auto c = ftell(f);

Upvotes: 1

Views: 556

Answers (3)

MSalters
MSalters

Reputation: 179907

boost::file_size returns the largest available integer type, so at least 64 bits. Works on all major platforms.

Upvotes: 0

Remus Rusanu
Remus Rusanu

Reputation: 294297

The POSIX API uses lseek which takes a off_t argument.

Windows API uses SetFilePointerEx which takes a LARGE_INTEGER argument.

And @Necrolis told you the clib MSVC extension...

Upvotes: 2

Necrolis
Necrolis

Reputation: 26171

MSVC has 64 bit variants of most C stdlib file functions which allow you to work with files larger that 4GB, in your case, see _ftelli64. There is also _filelengthi64 for descriptors (which you can get using _fileno).

Upvotes: 3

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