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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 
#include 

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 << ""
";
}

 

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

Recipe 4.9

Building C++ Applications

Code Organization

Numbers

Strings and Text

Dates and Times

Managing Data with Containers

Algorithms

Classes

Exceptions and Safety

Streams and Files

Science and Mathematics

Multithreading

Internationalization

XML

Miscellaneous

Index

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C++ Cookbook
Secure Programming Cookbook for C and C++: Recipes for Cryptography, Authentication, Input Validation & More
ISBN: 0596003943
EAN: 2147483647
Year: 2006
Pages: 241
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