Why is boost::is_regular_file
returning false? I am running the following code on wandbox.org
#include <boost/filesystem.hpp>
#include <iostream>
namespace filesys = boost::filesystem;
int main(){
filesys::path pathObj("used/for/test/DoesNotExist.json");
std::cout <<"is file "<< filesys::is_regular_file(pathObj) << std::endl;
return 0;
}
CodePudding user response:
This is the specified behaviour.
is_regular_file(p)
is equivalent tos.type() == file_type::regular
Notes
The throwing overload is additionally specified to throwstd::filesystem::filesystem_error
ifstatus(p)
would throw
status(p)
Ifp
does not exist, returnsfile_status(file_type::not_found)
file_type::not_found == file_type::regular
is false.
CodePudding user response:
I want to test if it's a path containing a file or not. Regardless if the file exists or not. Just Is – Hani Gotc 34 mins ago
Unless a file exists it can be either. It could even be a fifo, device node or UNIX domain socket. That's because the name means nothing about the type.
Simple demo: Live On Coliru
#include <boost/filesystem.hpp>
#include <iostream>
#include <iomanip>
namespace fs = boost::filesystem;
using boost::filesystem::path;
static inline std::ostream& operator<<(std::ostream& os, fs::file_type t) {
switch (t) {
case fs::file_type::block_file: return os << "block_file";
case fs::file_type::character_file: return os << "character_file";
case fs::file_type::directory_file: return os << "directory_file";
case fs::file_type::fifo_file: return os << "fifo_file";
case fs::file_type::file_not_found: return os << "file_not_found";
case fs::file_type::regular_file: return os << "regular_file";
case fs::file_type::reparse_file: return os << "reparse_file";
case fs::file_type::socket_file: return os << "socket_file";
case fs::file_type::symlink_file: return os << "symlink_file";
case fs::file_type::status_unknown: return os << "unknown/status error";
case fs::file_type::type_unknown:
default: return os << "unknown";
}
}
#define ACTION(statement) \
statement; \
std::cout << " ----- " << std::setw(50) << #statement << " " \
<< std::boolalpha; \
std::cout << "type(): " << status(spec).type() << std::endl; \
// std::cout << "is_regular_file(): " << is_regular_file(spec) << std::endl;
int main(){
ACTION(path spec("used/for/test/DoesNotExist.json"));
ACTION(create_directories(spec.parent_path()));
ACTION(create_directory(spec));
ACTION(remove(spec));
ACTION(std::ofstream(spec.native()));
ACTION(remove(spec));
path temp = fs::unique_path("/tmp/stackoverflow-%%%%%.tmp");
std::cout << "(temp = " << temp << ")\n";
ACTION(create_symlink(temp, spec));
ACTION(std::ofstream(temp.native()));
ACTION(remove(temp));
ACTION(remove(spec));
ACTION(create_symlink(fs::temp_directory_path(), spec));
ACTION(remove(spec));
}
Prints e.g.
----- path spec("used/for/test/DoesNotExist.json") type(): file_not_found
----- create_directories(spec.parent_path()) type(): file_not_found
----- create_directory(spec) type(): directory_file
----- remove(spec) type(): file_not_found
----- std::ofstream(spec.native()) type(): regular_file
----- remove(spec) type(): file_not_found
(temp = "/tmp/stackoverflow-e4bcc.tmp")
----- create_symlink(temp, spec) type(): file_not_found
----- std::ofstream(temp.native()) type(): regular_file
----- remove(temp) type(): file_not_found
----- remove(spec) type(): file_not_found
----- create_symlink(fs::temp_directory_path(), spec) type(): directory_file
----- remove(spec) type(): file_not_found
As you can see the file type changes depending on the situation.
Alternative
Perhaps you want to respond to the common naming convention where directory filenames have no extension:
#include <boost/filesystem.hpp>
#include <iostream>
using boost::filesystem::path;
int main() {
for (path p : {
"used/for/test/DoesNotExist.json",
"used/for/test",
"used/for/test/",
})
std::cout << p << " has extension: " << std::boolalpha
<< p.has_extension() << " (" << p.extension() << ")\n";
}
Prints
"used/for/test/DoesNotExist.json" has extension: true (".json")
"used/for/test" has extension: false ("")
"used/for/test/" has extension: false ("")