String.format throws incorrect format exception when there is an extra } in the string. What is the best way to resolve this?

Question

String.format throws incorrect format exception when there is an extra } in the string as shown in the snippet below

 var input = "1";
 var data = string.Format(@"{0}}", input);

I was able to resolve the issue by adding an extra } as shown below

var data = string.Format(@"{0}}}", input);

However I need to know if there is any better solution to this issue

`}` is a special character in the formatting context that needs to be escaped. Do you want a more clean and readable way ? — Zein Makki, Aug 08 '16 at 05:39
@user3185569 When i have a large json within the string the escaping by using an extra } character would make the code ugly .Is there a cleaner way to do it — Shaiju Janardhanan, Aug 08 '16 at 05:40
http://stackoverflow.com/questions/91362/how-to-escape-braces-curly-brackets-in-a-format-string-in-net — ah_hau, Aug 08 '16 at 05:43
I think string interpolation would be cleaner `$"{{{input}}}"` — Zein Makki, Aug 08 '16 at 05:45
@user3185569 if he has access to them depending on his version (and that just save a few keystroke) — Sehnsucht, Aug 08 '16 at 05:46
@Sehnsucht But it is cleaner as VS Formats the code and change the color to differentiate `{input}` from `{{` and `}}`. — Zein Makki, Aug 08 '16 at 05:48

score 3 · Accepted Answer · answered Aug 08 '16 at 06:08

3

I would highly recommend using C# 6 String Interpolation feature as it is more readable and maintainable:

var data = $"{{{input}}}";

When the string grows large, you'll see the benefit of Visual Studio formatting and coloring your string like this:

answered Aug 08 '16 at 06:08

Zein Makki

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that looks a lot cleaner. Thanks. But one small doubt, does the substitution of parameters result in creation of a new string everytime a substitution is made? – Shaiju Janardhanan Aug 08 '16 at 06:18
@ShaijuJanardhanan The compiler transforms the above into `String.Format` behind the scenes. So this is just a syntactic sugar, nothing different from your approach expect that it is cleaner and more readable and maintainable. – Zein Makki Aug 08 '16 at 06:21

score 1 · Answer 2 · answered Aug 08 '16 at 05:41

No, this is the intended functionality. From the docs:

How do I include literal braces ("{" and "}") in the result string? A single opening or closing brace is always interpreted as the beginning or end of a format item. To be interpreted literally, it must be escaped. You escape a brace by adding another brace ("{{" and "}}" instead of "{" and "}"), as in the following method call:

result = String.Format("The text has {0} '{{' characters and {1} '}}' characters.", 
             nOpen, nClose);

String.format throws incorrect format exception when there is an extra } in the string. What is the best way to resolve this?

2 Answers2