Rewrite this array manipulation using a lambda function?

Question

I have this routine which alters all elements within an array...

 for (int i = 0; i < sOutputFields.GetUpperBound(0); i ++)
 {
 sOutputFields[i] = clsSQLInterface.escapeIncoming(sOutputFields[i]);
 }

sOutputFields is a one dimensional string array. escapeIncoming() is a function which returns a string.

I thought this could be re-written thus..

 sOutputFields.Select(el => clsSQLInterface.escapeIncoming(el));

..but this appears to do nothing (though does not throw an exception). So I tried..

 sOutputFields = 
 (string[])sOutputFields.Select(el => clsSQLInterface.escapeIncoming(el));

..but I get this exception at execution time..

"Unable to cast object of type 'WhereSelectArrayIterator`2[System.String,System.String]' to type 'System.String[]'."

how to fix?

• asawyer: Query results are immutable, and => is not a assigment operator.
• Max: Your LINQ code does not rewrite, rather it creates a new collection

Answer 1

A Select doesn't return an object that can be explicitly cast to an array. You'd need to do sOutputFields.Select(el => clsSQLInterface.escapeIncoming(el)).ToArray<string>() in your assignment.

Answer 2

The return type is an IEnumerable, you need to convert to an array:

sOutputFields = sOutputFields.Select(el => clsSQLInterface.escapeIncoming(el)).ToArray();

• El Ronnoco: Thanks :) I see the ToArray<string>() is not required, just ToArray(). Why is that?

Answer 3

use:

sOutputFields = sOutputFields.Select(el => clsSQLInterface.escapeIncoming(el)).ToArray();

Answer 4

sOutputFields = sOutputFields.Select(el => clsSQLInterface.escapeIncoming(el)).ToArray();