std::experimental::filesystem::resize_file (3) - Linux Man Pages
Defined in header <experimental/filesystem>
void resize_file(const path& p, std::uintmax_t new_size); (filesystem TS)
void resize_file(const path& p, std::uintmax_t new_size, error_code& ec);
Changes the size of the regular file named by p as if by POSIX truncate: if the file size was previously larger than new_size, the remainder of the file is discarded. If the file was previously smaller than new_size, the file size is increased and the new area appears as if zero-filled.
p - path to delete
new_size - size that the file will now have
ec - out-parameter for error reporting in the non-throwing overload
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
On systems that support sparse files, increasing the file size does not increase the space it occupies on the file system: space allocation takes place only when non-zero bytes are written to the file.
demonstrates the effect of creating a sparse file on the free space
// Run this code