Can you populate a $variable$ within a string?

Question

I have what I'll call a template I pull out of some XML that shows the format the remote files are stored. So for example: https:// /whatever/file$number$.mp4 So I have this in a string. I also know that the $number$ starts with 1 and ends with 300. So if I do a loop to retrieve all the files do I need to strip it down to say https:// /whatever/file Then as part of the loop apend the number and the .mp4? Or can you automatically replace $number$ within the existing string with each number as you loop thru? Thanks. JR

John Riker · Answer

Right, but if I left the string as: https:// /whatever/file_$number$.mp4 could I on the fly replace $number$ dynamically? Thinking it isn't without stripping out the $number$ but was curious if there was a way to leave the string intact and just use it as is. Something like string str = "https:// /whatever/file_$number$.mp4" ; for ( int number = 1; number { process it } Or maybe even if you replaced $number$ with {number} within the string would it be replaceable? I know it's a minor nuance but curious.

John Riker · Answer

Thanks, one other thing with this. Maybe deserves a separate question. If the number of files I need to download isn't fully known. So for example the file duration is a certain length, and each segment is a particular duration so you kind of know what the total number of files are but not 100% sure. So from that perspective you could under estimate and not get them all, or over estimate and cause an error. What I was thinking of doing was to calculate what I think it is and then estimate slightly higher. Or just have a potential number of files way beyond what I would ever need. So was thinking of some kind of loop where I start at 1 and go to let's say 10,000 for the filename numbers and when it errors finish. is there a way to do like: While WebException not 404 do { Loop thru the numbers with like: using (WebClient client = new WebClient()) client.DownloadFile(url + number + ".m4v", DownloadTempPath + "filename" + number + ".m4v"); }

Amit Gupta · Answer

There were plenty of ways to achieve, you can try Replace function too string str = "https:///whatever/file_$number$.mp4"; for (int number = 1; number < 5; number++) { var file = str.Replace($number$,number.ToString()); }

Sachin Singh · Answer

i don't think, that is possible however you can use placeholder for ( int i = 0; i { String.Format( "https:// /whatever/file{0}" ,i); }

Sachin Singh · Answer

yes, you can append at run time while looping through it string str = "https:// /whatever/file" ; for ( int i = 0; i { str = str + i + ".mp4" ; }