Insert variable values in the middle of a string

Question

In C#: If I want to create a message like this: "Hi We have these flights for you: Flight A,B,C,D. Which one do you want"

where just the section in bold is dynamic and I pass its value at run time, but its left and right parts are fixed. I can create something like LeftMessage + those variables + RightMessage to create this. But I was wondering if there is a way of doing it all at once without the need to create two separate left and right messages?

For translation purposes I am putting those left and right messages inside string resources so now I have two separate string resources. Is there a way to do it all at once?

Yes look up String.Join() method example String.Join(', ', someVariable) or String.Format("message {0}. and use the following param counter(s) for the rest of the text params {1} {2} {3}, etc — MethodMan, Oct 23 '12 at 15:12

score 126 · Answer 1 · edited Nov 27 '20 at 16:17

126

There's now (C# 6) a more succinct way to do it: string interpolation.

From another question's answer:

In C# 6 you can use string interpolation:
string name = "John";
string result = $"Hello {name}";
The syntax highlighting for this in Visual Studio makes it highly readable and all of the tokens are checked.

edited Nov 27 '20 at 16:17

Legolas

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answered Sep 10 '15 at 22:50

Vimes

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score 63 · Accepted Answer · edited Sep 23 '20 at 22:38

63

You can use string.Format:

string template = "Hi We have these flights for you: {0}. Which one do you want";
string data = "A, B, C, D";
string message = string.Format(template, data);

You should load template from your resource file and data is your runtime values.

Be careful if you're translating to multiple languages, though: in some cases, you'll need different tokens (the {0}) in different languages.

edited Sep 23 '20 at 22:38

TylerH

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answered Oct 23 '12 at 15:12

Dan Puzey

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re: tokens - I can't find any info on this, do you mean that if using a different language I would need to use the equivalent of {0} in the other language? – A_L Feb 03 '15 at 12:40

codingbiz · Answer 3 · 2016-08-15T16:59:45.210

36

Use String.Format

Pre C# 6.0

string data = "FlightA, B,C,D";
var str = String.Format("Hi We have these flights for you: {0}. Which one do you want?", data);

C# 6.0 -- String Interpolation

string data = "FlightA, B,C,D";
var str = $"Hi We have these flights for you: {data}. Which one do you want?";

http://www.informit.com/articles/article.aspx?p=2422807

edited Aug 15 '16 at 16:59

answered Oct 23 '12 at 15:12

codingbiz

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my code tool (resharper) suggests an autocorrect from the first form to the second one, indicating that that is (by default) the preferred syntax. – Andrew Hill Jan 05 '18 at 01:16

Paolo Falabella · Answer 4 · 2012-10-23T15:17:40.107

String.Format("Hi We have these flights for you: {0}. Which one do you want",
                              flights);

EDIT: you can even save the "template" string separately (for instance you could store it in a configuration file and retrieve it from there), like this:

string flights = "Flight A, B,C,D";

string template = @"Hi We have these flights for you: {0}. Which one do you want";
Console.WriteLine(String.Format(template, flights));

EDIT2: whoops, sorry I see that @DanPuzey had already suggested something very similar to my EDIT (but somewhat better)

score 2 · Answer 5 · answered Oct 23 '12 at 15:11

1 You can use string.Replace method

var sample = "testtesttesttest#replace#testtesttest";
var result = sample.Replace("#replace#", yourValue);

2 You can also use string.Format

var result = string.Format("your right part {0} Your left Part", yourValue);

3 You can use Regex class

score 0 · Answer 6 · answered Jan 15 '20 at 17:06

I would use a StringBuilder class for doing string manipulation as it will more efficient (being mutable)

string flights = "Flight A, B,C,D";
StringBuilder message = new StringBuilder();
message.Append("Hi We have these flights for you: ");
message.Append(flights);
message.Append(" . Which one do you want?");

Insert variable values in the middle of a string

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