CODEWITHSUNDEEP
c#string
LastBye
LastBye

Reputation: 1173

String Insertion won't take any effect

Inserting a string into a string doesn't appear to have any effect. I'm using the following code:

string stNum = string.Format("{0:00}", iValue);
DesiredCode.Insert(0, stNum);
txtCode.Text = DesiredCode;

Breakpoints show stNum has the desired value, and DesiredCode is also as we would expect before insertion. But after insertion, nothing will happen and the DesiredCode is the same as before!

Can someone please point me in the right direction as to what I'm doing wrong?

Upvotes: 0

Views: 103

Answers (3)

Adam Maras
Adam Maras

Reputation: 26843

Strings are immutable in C#. What this means is that you need to assign the return value of String.Insert to a string variable after the operation in order to access it.

string stNum = string.Format("{0:00}", iValue);
DesiredCode = DesiredCode.Insert(0, stNum);
txtCode.Text = DesiredCode;

Upvotes: 2

sll
sll

Reputation: 62484

Strings are immutable!

DesiredCode = DesiredCode.Insert(0, stNum);

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1499780

Strings are immutable. All the methods like Replace and Insert return a new string which is the result of the operation, rather than changing the data in the existing string. So you probably want:

txtCode.Text = DesiredCode.Insert(0, stNum);

Or for the whole block, using direct ToString formatting instead of using string.Format:

txtCode.Text = DesiredCode.Insert(0, iValue.ToString("00"));

Or even clearer, in my opinion, would be to use string concatenation:

txtCode.Text = iValue.ToString("00") + DesiredCode;

Note that none of these will change the value of DesiredCode. If you want to do that, you'd need to assign back to it, e.g.

DesiredCode = iValue.ToString("00") + DesiredCode;
txtCode.Text = DesiredCode;

Upvotes: 7

Related Questions