String.Replace using multiple values

Question

I was looking at some code from a co-worker and it looks as though they're using a Char Array in their String.Replace:

txtPAPTransit.Text = g_aAllBranches(instApplication.branchForCumisReporting.ToLower).transit.ToString.Replace({" "c, "-"c}, "").Substring(3)

Which doesn't remove the "-" from the string in the textbox (the string being 123-45678). When I try it making the Substring as 4 instead of 3, it works. Which strikes me as very odd, why would it behave like this in this case when the index is 0 based?

When I write the replace like this it works fine:

txtPAPTransit.Text = g_aAllBranches(instApplication.branchForCumisReporting.ToLower).transit.ToString.Replace("-"c, "").Substring(3)

Afterwards the string appears as 45678, which is the correct result.

Why would it work in the case of replacing the substring with 4 as I mention above? And why does it have a problem with the char array?

Why would you expect the first example to remove the "-" from the textbox? The first argument is what to remove, in that case, it would be the space that would be replaced with the - — Scott Marcus
– Scott Marcus, Commented Mar 15, 2016 at 20:19
@ScottMarcus But if you notice the .Replace has a char array in its 'oldValue' position. .Replace({" "c, "-"c,"") which if the logic were correct, would mean that it would replace either a whitespace or a dash with nothing. But the Replace doesn't seem to be able to handle this. — Him_Jalpert
– Him_Jalpert, Commented Mar 15, 2016 at 20:23
it doesnt remove the "-" because the Replace usage is wrong. {" "c, "-"c} will equate to " " + " -" not act as a multiple replace for any space and any "-". Thus nothing is removed. Replace takes a single char or a string: an array of char is a string so nothing happens unless it is "123 -45678". .Replace(" "c, "").Replace("-"c, "") would be the way to do both/either — Ňɏssa Pøngjǣrdenlarp
– Ňɏssa Pøngjǣrdenlarp, Commented Mar 15, 2016 at 20:24
Tricky code for no reason. Your coworker seems to be tired of VB — Artem Koshelev
– Artem Koshelev, Commented Mar 15, 2016 at 20:27

Ňɏssa Pøngjǣrdenlarp · Accepted Answer · 2016-03-15 21:07:31Z

3

The Replace usage is not correct - or your co-workers understanding of it is flawed. The 2 overloads are:

- String.Replace(Char, Char)  
- String.Replace(String, String)

So, Replace({" "c, "-"c}, "") will not act to replace any space and any dash with String.Empty. Instead, since a char array is a string, it will look to replace " -" (space+dash) as in "123 -45678".

The correct way to replace either would be:

Dim sample = "123- ABCDEFG"     
newTxt = sample.Replace(" "c, "").Replace("-"c, "")

"123ABCDEFG"

edited Mar 15, 2016 at 21:07

answered Mar 15, 2016 at 20:43

Ňɏssa Pøngjǣrdenlarp

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2 Comments

Him_Jalpert Over a year ago

Thanks for the help! I've got it written the proper way with the 2 Replace functions and it works great now!

Ňɏssa Pøngjǣrdenlarp Over a year ago

Glad to help - that long, long expression in the Q makes it hard to follow wothout an example because the "problem part" is scrolled off

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