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std::experimental::filesystem::file_size

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< cpp‎ | experimental‎ | fs
 
 
Experimental
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Filesystem library (filesystem TS)
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Defined in header <experimental/filesystem>
std::uintmax_t file_size( const path& p );
std::uintmax_t file_size( const path& p, error_code& ec );
(1) (filesystem TS)

Returns the size of the regular file p, determined as if by reading the st_size member of the structure obtained by POSIX stat (symlinks are followed).

Attempting to determine the size of a directory (as well as any other file that is not a regular file or a symlink) is treated as an error.

The non-throwing overload returns returns -1 on errors.

Contents

[edit] Parameters

p - path to examine
ec - out-parameter for error reporting in the non-throwing overload

[edit] Return value

The size of the file, in bytes.

[edit] Exceptions

The overload that does not take an error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argument and the OS error code as the error code argument. std::bad_alloc may be thrown if memory allocation fails. The overload taking an error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. This overload has
noexcept specification:  
noexcept
  

[edit] Example

#include <experimental/filesystem>
#include <fstream>
#include <iostream>
namespace fs = std::experimental::filesystem;
 
int main()
{
    fs::path p = fs::current_path() / "example.bin";
    std::ofstream(p).put('a'); // create file of size 1
    std::cout << "File size = " << fs::file_size(p) << '\n';
    fs::remove(p);
 
    try
    {
        fs::file_size("/dev"); // attempt to get size of a directory
    }
    catch (fs::filesystem_error& e)
    {
        std::cout << e.what() << '\n';
    }        
}

Possible output:

File size = 1
filesystem error: cannot get file size: Is a directory [/dev]

[edit] See also

changes the size of a regular file by truncation or zero-fill
(function) [edit]
determines available free space on the file system
(function) [edit]