RegEx vs string manipulation functions: What is better

Question

If I have to find let's say a word in a sentence, i can think of two approaches

1. Using string.IndexOf
2. Using Regex

Which one is better in terms of performance or best practice

Answer 1

If it's fairly straightforward to do something without regex, it's almost always cheaper that way. String.IndexOf (or String.Contains) is definitely an example of this.