Since you're using 'system', I presume that the external app in question can be launched via command prompt. In that case, you've got an easy solution. Just add "start " to the front of what you're sending into 'system'. This will tell Windows to run the rest of the command in a new "space" and will immediately return control back to your script.

For example, if you were launching notepad, you could do it with the following line of code:

system("notepad");

That would cause the script to wait until notepad was closed. Instead, modify it to be like this:

system("start notepad");

You'll see a command prompt appear, notepad gets opened, the command prompt disappears, and your script continues on. Just apply this to your script/app code in launching the external app and you should be good to go.

If you want to know more about the various options for the 'start' command, just open a command prompt and type start /? to see the help information.