std::filesystem::file_size
std::filesystem::file_size
Defined in header <filesystem>
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(1) | (since C++17) |
If p
does not exist, reports an error.
For a regular file p
, returns the size determined as if by reading the st_size
member of the structure obtained by POSIX stat (symlinks are followed).
The result of attempting to determine the size of a directory (as well as any other file that is not a regular file or a symlink) is implementation-defined.
The non-throwing overload 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 std::error_code&
parameter throws filesystem_error on underlying OS API errors, constructed with p
as the first path argument and the OS error code as the error code argument. The overload taking a std::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. Any overload not marked noexcept
may throw std::bad_alloc
if memory allocation fails.
Example
#include <iostream>
#include <fstream>
#include <filesystem>
namespace fs = std::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
(C++17) |
changes the size of a regular file by truncation or zero-fill (function) |
(C++17) |
determines available free space on the file system (function) |
returns the size of the file to which the directory entry refers (public member function of std::filesystem::directory_entry) |
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