NAME¶

std::experimental::filesystem::file_size - std::experimental::filesystem::file_size

Synopsis¶

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

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.

Parameters¶

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

Return value¶

The size of the file, in bytes.

Exceptions¶

The overload that does not take a 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 a 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

Example¶

// Run this code

#include <iostream>
#include <fstream>
#include <experimental/filesystem>
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]

See also¶

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