Hi, I'd like to ask you if someone could help me about this topic: Reading multiple files For example, I have a serial of txt files named as: file_01.txt, file_02.txt, file_03.txt and so on file_10.txt, etc. I want to read sequentially each of theme with a loop, but I do not know how I can indicates to idl that in the name of the file the number 01, 02 , 13,.... is a progressive number that make a distinction for each file. I guess that make this distinction I can use this information as an index for a loop. If anybody knows how to help, please let me know!! Thanks in advance