string[] books = new string[] { "Java", "SQL", "OOPS Concepts", "DotNet Basics"};

Predicate<string> longBooks = delegate(string book) { return book.Length > 5; };
int numberOfBooksWithLongNames = books.Count(longBooks);

string[] books = new string[] { "Java", "SQL", "OOPS Concepts", "DotNet Basics"};

Func<string, bool> longBooks = delegate(string book) { return book.Length > 5; };
int numberOfBooksWithLongNames = books.Count(longBooks);

var result = books.Count(x => x.Length > 5);

public bool IsThisALongBookTitle(string book)
{
    return book.Length > 5;
}

var result = books.Count(IsThisALongBookTitle);

string[]' does not contain a definition for 'Count' and the best extension method
 overload 'System.Linq.Enumerable.Count<TSource>
(System.Collections.Generic.IEnumerable<TSource>, System.Func<TSource,bool>)'
has some invalid arguments

Argument 2: cannot convert from 'System.Predicate<string>' to
'System.Func<string,bool>'

int numberOfBooksWithLongNames = books.AsEnumberable().Count(s => longBooks(s));
int numberOfBooksWithLongNames = new List<string>(books).Count(s => longBooks(s));
int numberOfBooksWithLongNames = books.Count(s => longBooks(s));

books.Count(a = > a.Length > 5);