Defined in header <filesystem> | ||
|---|---|---|
std::uintmax_t file_size( const std::filesystem::path& p ); std::uintmax_t file_size( const std::filesystem::path& p, std::error_code& ec ); | (1) | (since C++17) |
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.
| p | - | path to examine |
| ec | - | out-parameter for error reporting in the non-throwing overload |
The size of the file, in bytes.
std::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 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. This overload has noexcept specification: noexcept#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 boost::filesystem::file_size: Operation not permitted: "/dev"
|
(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) |
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