Extracting a Path from a Full Path and Filename

2017-11-03 09:05:03

Problem

You have the full path of a filename, e.g., d:appssrcfoo.c, and you need to get the pathname, d:appssrc.

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 #include 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) << "" "; }

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 #include #include 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; } return(EXIT_SUCCESS); }

Sample output from Example 10-24 looks like this:

D:srcccbc10>binGetPathBoost.exe c:windowssystem321033 c:/windows/system32

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