Say, i want to create a file compressor-extractor(using C programming language). When the file is compressed, it has the extension ".jisan" ... is there any way that when i double click on the compressed file(example: file.jisan), it will extract itself automatically?

If MS-Windows you have to add an entry in the registry under HKEY_CLASSES_ROOT. If you run regedit.exe and scroll through that key you will see how others do the same thing, just make sure you don't accidentally change anything because you can potentially screw up the entire operating system.