how do I set a character at an index in a string in c#?

Question

someString[someRandomIdx] = 'g'; 

will give me an error.

How do I achieve the above?

Answer 1

If it is of type string then you can't do that because strings are immutable - they cannot be changed once they are set.

To achieve what you desire, you can use a StringBuilder

StringBuilder someString = new StringBuilder("someString");  someString[4] = 'g'; 

Update

Why use a string, instead of a StringBuilder? For lots of reasons. Here are some I can think of:

• Accessing the value of a string is faster.
• strings can be interned (this doesn't always happen), so that if you create a string with the same value then no extra memory is used.
• strings are immutable, so they work better in hash based collections and they are inherently thread safe.

Answer 2

C# strings are immutable. You should create a new string with the modified contents.

 char[] charArr = someString.ToCharArray();  charArr[someRandomIdx] = 'g'; // freely modify the array  someString = new string(charArr); // create a new string with array contents.