Indexing of source code can work but it has limitations. It helps to think about how an index search works. An index contains a list of terms that have been extracted from files and it's those terms that are searched in any subsequent searches. For normal text documents identifying terms is usually pretty straight forward, ie space separated sequences of characters or numbers.
Source code is much harder. For example,
*name[++p] = "sample";
Would result in three terms being added to the index:
If basic searching for variable names, comments etc is all you require then indexing should work OK. Support for more complex source code indexing is something that will be improved over future versions of the product.