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C++ Cookbook
book

C++ Cookbook

by D. Ryan Stephens, Christopher Diggins, Jonathan Turkanis, Jeff Cogswell
November 2005
Beginner to intermediate content levelBeginner to intermediate
594 pages
16h 23m
English
O'Reilly Media, Inc.
Content preview from C++ Cookbook

10.15. Extracting a Path from a Full Path and Filename

Problem

You have the full path of a filename, e.g., d:\apps\src\foo.c, and you need to get the pathname, d:\apps\src.

Solution

Use the same technique as the previous two recipes by invoking rfind and substr to find and get what you want from the full pathname. See Example 10-23 for a short sample program.

Example 10-23. Get the path from a full path and filename

#include <iostream>
#include <string>

using std::string;

string getPathName(const string& s) {

   char sep = '/';

#ifdef _WIN32
   sep = '\\';
#endif

   size_t i = s.rfind(sep, s.length());
   if (i != string::npos) {
      return(s.substr(0, i));
   }

   return("");
}

int main(int argc, char** argv) {

   string path = argv[1];

   std::cout << "The path name is \"" << getPathName(path) << "\"\n";
}

Discussion

Example 10-23 is trivial, especially if you’ve already looked at the previous few recipes, so there is no more to explain. However, as with many of the other recipes, the Boost Filesystem library provides a way to extract everything but the last part of the filename with its branch_path function. Example 10-24 shows how to use it.

Example 10-24. Getting the base path

#include <iostream> #include <cstdlib> #include <boost/filesystem/operations.hpp> using namespace std; using namespace boost::filesystem; int main(int argc, char** argv) { // Parameter checking... try { path p = complete(path(argv[1], native)); cout << p.branch_path().string() << endl; } catch (exception& e) { cerr << e.what() << endl; } ...
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Publisher Resources

ISBN: 0596007612Supplemental ContentErrata Page