The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <iostream>
#include <string>
using namespace std;
int main (int argc, char* argv[])
{
string filename, basename, extname, tmpname;
const string suffix("tmp");
// for each command-line argument (which is an ordinary C-string)
for (int i=1; i<argc; ++i) {
// process argument as filename
filename = argv[i];
// search period in filename
string::size_type idx = filename.find('.');
if (idx == string::npos) {
// filename does not contain any period
tmpname = filename + '.' + suffix;
}
else {
// split filename into base name and extension
// - base name contains all characters before the period
// - extension contains all characters after the period
basename = filename.substr(0, idx);
extname = filename.substr(idx+1);
if (extname.empty()) {
// contains period but no extension: append tmp
tmpname = filename;
tmpname += suffix;
}
else if (extname == suffix) {
// replace extension tmp with xxx
tmpname = filename;
tmpname.replace (idx+1, extname.size(), "xxx");
}
else {
// replace any extension with tmp
tmpname = filename;
tmpname.replace (idx+1, string::npos, suffix);
}
}
// print filename and temporary name
cout << filename << " => " << tmpname << endl;
}
}