10.16. Replacing a File Extension
Problem
Given a filename, or a path and
filename, you want to replace the file’s extension. For example, if you are
given thesis.tex
, you want to convert it to thesis.txt
.
Solution
Use string
’s rfind
and replace
member functions to find
the extension and replace it. Example
10-25 shows you how to do this.
Example 10-25. Replacing a file extension
#include <iostream> #include <string> using std::string; void replaceExt(string& s, const string& newExt) { string::size_type i = s.rfind('.', s.length()); if (i != string::npos) { s.replace(i+1, newExt.length(), newExt); } } int main(int argc, char** argv) { string path = argv[1]; replaceExt(path, "foobar"); std::cout << "The new name is \"" << path << "\"\n"; }
Discussion
This solution is similar to the ones in the preceding recipes, but in this case I used
replace
to replace a portion of the string with a new
string. replace
has three parameters. The first
parameter is the index where the replace
should begin,
and the second is the number of characters to delete from the destination string. The
third parameter is the value that will be used to replace the deleted portion of the
string.
See Also
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