Question

I have 2 strings, A and B. A contains “HelloHowAreYou”. B contains “Bingo”. I want to replace string A with string B resulting to “BingoHowAreYou”. Any tips on how to do this? Even a keyword is suffice.

I know this is kinda newbie, but i dont want to hunt all msdn doc just to find this simple things. As i said, a simple guide/keyword pointing to the right direction is enough.

Edit:

Assuming i dont know the contents of the strings. can i just use the replace? Thanks for the fast reply.

Answer 1

Fortunately, you don’t need to hunt down all of MSDN… just the String class.

As others have said, String.Replace(string, string) is probably what you’re looking for:

string a = "HelloHowAreYou";
string b = "Bingo";
string c = a.Replace("Hello", b); // Now the value of c is "BingoHowAreYou"

Alternatively, if you’re trying to just replace the first characters of a with the same number of characters in b, something like this would do instead, using Substring and string concatenation:

string c = b.Length >= a.Length ? b : b + a.Substring(b.Length);

(Depending on exactly what you want to do when b is longer than a of course.)

A few things worth knowing though:

• This is a good example of library functionality – so you won’t find a C# keyword for it. While some C# keywords do interact with the library (e.g. using statements that know about the IDisposable type) most of the time, if you’re interested in something which sounds like a library feature, you should be looking in the library documentation rather than looking for a keyword.
• Strings are immutable: String.Replace doesn’t change the existing string – it returns a new string with the appropriate result. Some other types follow the same pattern – in particular value types such as DateTime are typically immutable, so DateTime.AddDays doesn’t change the existing value, but returns a new value.
• It’s worth getting used to looking through MSDN. You’re likely to do it a lot, so having a look through the string class now would be good practice.