Examples for IEnumerable and IQueryable interface in C#

Examples for IEnumerable and IQueryable interface:

Examples using IEnumerable:

• Filtering with LINQ to Objects:

IEnumerable<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
IEnumerable<int> evenNumbers = numbers.Where(n => n % 2 == 0);

• Projection with LINQ to Objects:

IEnumerable<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
IEnumerable<string> numberStrings = numbers.Select(n => n.ToString());

• Aggregation with LINQ to Objects:

IEnumerable<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
int sum = numbers.Sum();

• Iteration with foreach:

IEnumerable<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
foreach (int number in numbers)
{
    Console.WriteLine(number);
}

• Custom Query using LINQ to Objects:

IEnumerable<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
IEnumerable<int> squaredNumbers = numbers.Select(n => n * n);

Examples using IQueryable:

• Filtering with LINQ to Entities (EF Core):

IQueryable<Product> products = dbContext.Products;
IQueryable<Product> expensiveProducts = products.Where(p => p.Price > 100);

• Projection with LINQ to Entities (EF Core):

IQueryable<Product> products = dbContext.Products;
IQueryable<string> productNames = products.Select(p => p.Name);

• Aggregation with LINQ to Entities (EF Core):

IQueryable<Product> products = dbContext.Products;
decimal totalSales = products.Sum(p => p.Price * p.QuantitySold);

• Deferred Execution with LINQ to SQL:

IQueryable<Customer> customers = dbContext.Customers;
var query = customers.Where(c => c.Country == "USA");
var filteredCustomers = query.ToList(); // Executes the query here

• Combining Queries with LINQ to SQL:

IQueryable<Product> products = dbContext.Products;
IQueryable<Product> discountedProducts = products.Where(p => p.Discount > 0).OrderBy(p => p.Price);