Easy way to remove extension from a filename?

Question

I am trying to grab the raw filename without the extension from the filename passed in arguments:

int main ( int argc, char *argv[] )
{
    // Check to make sure there is a single argument
    if ( argc != 2 )
    {
        cout<<"usage: "<< argv[0] <<" <filename>\n";
        return 1;
    }

    // Remove the extension if it was supplied from argv[1] -- pseudocode
    char* filename = removeExtension(argv[1]);

    cout << filename;

}

The filename should for example be "test" when I passed in "test.dat".

Answer 1

size_t lastindex = fullname.find_last_of("."); 
string rawname = fullname.substr(0, lastindex); 

Beware of the case when there is no "." and it returns npos

Answer 2

This works:

std::string remove_extension(const std::string& filename) {
    size_t lastdot = filename.find_last_of(".");
    if (lastdot == std::string::npos) return filename;
    return filename.substr(0, lastdot); 
}

Answer 3

Since C++17 you can use std::filesystem::path::replace_extension with a parameter to replace the extension or without to remove it:

#include <iostream>
#include <filesystem>
 
int main()
{
    std::filesystem::path p = "/foo/bar.txt";
    std::cout << "Was: " << p << std::endl;
    std::cout << "Now: " << p.replace_extension() << std::endl;
}

Compile it with:

g++ -std=c++17 -O2 -Wall -pedantic -pthread main.cpp && ./a.out

Running the resulting binary leaves you with:

Was: "/foo/bar.txt"
Now: "/foo/bar"

However this does only remove the last file extension:

Was: "/foo/bar.tar.gz"
Now: "/foo/bar.tar"

Answer 4

In my opinion it is easiest, and the most readable solution:

#include <boost/filesystem/convenience.hpp>

std::string removeFileExtension(const std::string& fileName)
{
    return boost::filesystem::change_extension(fileName, "").string();
}

Answer 5

For those who like boost:

Use boost::filesystem::path::stem. It returns the filename without the last extension. So ./myFiles/foo.bar.foobar becomes foo.bar. So when you know you are dealing with only one extension you could do the follwing:

boost::filesystem::path path("./myFiles/fileWithOneExt.myExt");
std::string fileNameWithoutExtension = path.stem().string();

When you have to deal with multiple extensions you might do the following:

boost::filesystem::path path("./myFiles/fileWithMultiExt.myExt.my2ndExt.my3rdExt");
while(!path.extension().empty())
{
    path = path.stem();
}

std::string fileNameWithoutExtensions = path.stem().string();

(taken from here: http://www.boost.org/doc/libs/1_53_0/libs/filesystem/doc/reference.html#path-decomposition found in the stem section)

BTW works with rooted paths, too.

Answer 6

The following works for a std::string:

string s = filename;
s.erase(s.find_last_of("."), string::npos);

Answer 7

More complex, but with respect to special cases (for example: "foo.bar/baz", "c:foo.bar", works for Windows too)

std::string remove_extension(const std::string& path) {
    if (path == "." || path == "..")
        return path;

    size_t pos = path.find_last_of("\\/.");
    if (pos != std::string::npos && path[pos] == '.')
        return path.substr(0, pos);

    return path;
}

Answer 8

You can do this easily :

string fileName = argv[1];
string fileNameWithoutExtension = fileName.substr(0, fileName.rfind("."));

Note that this only work if there is a dot. You should test before if there is a dot, but you get the idea.

Answer 9

In case someone just wants a simple solution for windows:

Use PathCchRemoveExtension ->MSDN

... or PathRemoveExtension (deprecated!) ->MSDN

Answer 10

Try the following trick to extract the file name from path with no extension in c++ with no external libraries in c++ :

#include <iostream>
#include <string>

using std::string;

string getFileName(const string& s) {
char sep = '/';
#ifdef _WIN32
sep = '\\';
#endif
size_t i = s.rfind(sep, s.length());
if (i != string::npos) 
{
  string filename = s.substr(i+1, s.length() - i);
  size_t lastindex = filename.find_last_of("."); 
  string rawname = filename.substr(0, lastindex); 
  return(rawname);
}

return("");
}

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

string path = "/home/aymen/hello_world.cpp";
string ss = getFileName(path);
std::cout << "The file name is \"" << ss << "\"\n";
}

Answer 11

Just loop through the list and replace the first (or last) occurrence of a '.' with a NULL terminator. That will end the string at that point.

Or make a copy of the string up until the '.', but only if you want to return a new copy. Which could get messy since a dynamically allocated string could be a source of memory leak.

for(len=strlen(extension);len>= 0 && extension[len] != '.';len--)
     ;

char * str = malloc(len+1);

for(i=0;i<len;i++)
  str[i] = extension[i];

 str[i] = '\0'l