In this tutorial, we will write a simple utility program for listing directories recursively. Poco provides DirectoryIterator to iterate over all the items contained in a directory. We will also make use of DateTimeFormatter to format the last-modified timestamp in our local time zone instead of the default UTC. This utility mimics the behavior of ls -all.
The Poco here stands for the POCO C++ libraries and is not to be confused with Plain Old CLR Object.
Create a file named rec_dir.cc with the following code:
#include <Poco/DirectoryIterator.h>
#include <Poco/DateTimeFormatter.h>
#include <Poco/LocalDateTime.h>
#include <iostream>
#include <string>
using namespace Poco;
using namespace std;
void rec_dir(const string & path)
{
DirectoryIterator end;
for (DirectoryIterator it(path); it != end; ++it)
{
cout << (it->isDirectory() ? "d" : "-");
cout << (it->canRead() ? "r" : "-");
cout << (it->canWrite() ? "w" : "-");
cout << (it->canExecute() ? "x" : "-");
cout << "\t";
cout << it->getSize() << "\t";
LocalDateTime lastModified(it->getLastModified());
cout << DateTimeFormatter::format
(lastModified, "%Y-%m-%d %H:%M") << "\t";
cout << it->path() << (it->isDirectory() ?
"/" : it->canExecute() ? "*" : "") << endl;
if (it->isDirectory())
{
rec_dir(it->path());
}
}
}
int main(int argc, char **argv)
{
rec_dir(argc > 1 ? argv[1] : ".");
return 0;
}
Compile it and run:
$ g++ -o rec_dir rec_dir.cc -lPocoFoundation
$ ./rec_dir
-rwx 14223 2011-09-14 13:34 rec_dir*
drwx 4096 2011-09-14 12:52 testdir/
drwx 4096 2011-09-14 12:52 testdir/dir/
-rw- 941 2011-09-14 13:24 rec_dir.cc
-rw- 0 2011-09-14 12:43 somefile
You may also try ./rec_dir .. or ./rec_dir ~. It’s fun! :–)
The code is simple enough but these classes provided by Poco are powerful. You may check out DirectoryIterator and File for information about other usage.
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