Only one line of code is needed to join multiple mp3 files: copy /b *.mp3 c:\new.mp3. That’s all there is needed. The /b parameter ensures that the files are copied in binary format. *.mp3 defines the source directory of the files. You can easily add a drive and folder structure in front. The wildcard * defines that all mp3 will be joined alphanumerically by the command. It is possible to limit the files by adding letters or numbers to the command, e.g. m*.mp3 to join all mp3 starting with the letter m.

The last part c:\mp3 defines the target directory for the newly created file as well as its name. A possibility to join files with different filenames is also available. Simply use the command copy /b file1.mp3 + aaa.mp3 + r3f.mp3 c:\new.mp3 for this. You may use wildcards as well for the process.

Several applications like Audacity can also be used to merge music files. Mp3 Direct Cut is another one for the purpose.