public interface ICalculator<T>
    {
        T Add(T operand1, T operand2);
    }

    public class Calculator<T> : ICalculator<T>
    {
        public T Add(T operand1, T operand2)
        {
            return operand1 + operand2;
        }
    }

 Operator '+' cannot be applied to operands of type 'T' and 'T'

    public class Calculator2<T>
    {
        public T Sum(List<T> list)
        {
            T sum = 0;
            for (int i = 0; i < list.Count; i++)
                sum += list[i];
            return sum;
        }
    }

    public interface ICalculator<T>
    {
        T Add(T operand1, T operand2);
    }

    public class Int32Calculator : ICalculator<int>
    {
        public int Add(int operand1, int operand2)
        {
            return operand1 + operand2;
        }
    }

    public class AlgorithmLibrary<T> where T : new() 
    {
        private readonly ICalculator<T> _calculator;
        public AlgorithmLibrary(ICalculator<T> calculator)
        {
            _calculator = calculator;
        }

        public T Sum(List<T> items)
        {
            var sum = new T();
            for (var i = 0; i < items.Count; i++)
            {
                sum = _calculator.Add(sum, items[i]);
            }
            return sum;
        }
    }

 var result = new AlgorithmLibrary<int>(new Int32Calculator()).Sum(new List<int> { 1, 2, 3 });

    public class Algorithms<T> where T : new() 
    {
        public T Calculate(Func<T, T, T> add, IEnumerable<T> numbers)
        {
            var sum = new T();
            foreach (var number in numbers)
            {
                sum = add(sum, number);
            }
            return sum;
        }
    }

 var result = new Algorithms<int>().Calculate((a, b) => a + b, new[] { 1, 2, 3 });

    public class Calculator<T> : ICalculator<T>
    {
        public T Add(T operand1, T operand2)
        {
            return (dynamic)operand1 + operand2;
        }
    }

 var test = new Calculator<int>().Add(1, 2);

public T Add(T t1, T t2)
{
    if (typeof(T) == typeof(double))
    {
        var d1 = (double)t1;
        var d2 = (double)t2;
        return (T)(d1 + d2);
    }
    else if (typeof(T) == typeof(int)){
        var i1 = (int)t1;
        var i2 = (int)t2;
        return (T)(i1 + i2);
    }
    else ...
}

using System;
using System.Linq.Expressions;

namespace GenericsArithmetic
{
    public class Solution3
    {
        public T Add<T>(T a, T b)
        {
            var paramA = Expression.Parameter(typeof(T), "a");
            var paramB = Expression.Parameter(typeof(T), "b");

            var body = Expression.Add(paramA, paramB);
            var add = Expression.Lambda<Func<T, T, T>>(body, paramA, paramB).Compile();
            return add(a, b);
        }
    }
}

public static T Sum<T>(this IEnumerable<T> source)
{
    T sum = Operator<T>.Zero;
    foreach (T value in source)
    {
            sum = Operator.Add(sum, value);
    }
    return sum;
}
 

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Data.Objects;
using System.Diagnostics;
using System.Linq;
using System.Web;
using System.Web.Caching;

namespace EfSecondLevelCaching.Core
{
    public static class EfHttpRuntimeCacheProvider
    {
        #region Methods (6)

        // Public Methods (2) 

        public static IList<TEntity> ToCacheableList<TEntity>(
                            this IQueryable<TEntity> query,
                            int durationMinutes = 15,
                            CacheItemPriority priority = CacheItemPriority.Normal)
        {
            return query.Cacheable(x => x.ToList(), durationMinutes, priority);
        }

        /// <summary>
        /// Returns the result of the query; if possible from the cache, otherwise
        /// the query is materialized and the result cached before being returned.
        /// The cache entry has a one minute sliding expiration with normal priority.
        /// </summary>
        public static TResult Cacheable<TEntity, TResult>(
                            this IQueryable<TEntity> query,
                            Func<IQueryable<TEntity>, TResult> materializer,
                            int durationMinutes = 15,
                            CacheItemPriority priority = CacheItemPriority.Normal)
        {
            // Gets a cache key for a query.
            var queryCacheKey = query.GetCacheKey();

            // The name of the cache key used to clear the cache. All cached items depend on this key.
            var rootCacheKey = typeof(TEntity).FullName;

            // Try to get the query result from the cache.
            printAllCachedKeys();
            var result = HttpRuntime.Cache.Get(queryCacheKey);
            if (result != null)
            {
                debugWriteLine("Fetching object '{0}__{1}' from the cache.", rootCacheKey, queryCacheKey);
                return (TResult)result;
            }

            // Materialize the query.
            result = materializer(query);

            // Adding new data.
            debugWriteLine("Adding new data: queryKey={0}, dependencyKey={1}", queryCacheKey, rootCacheKey);
            storeRootCacheKey(rootCacheKey);
            HttpRuntime.Cache.Insert(
                    key: queryCacheKey,
                    value: result,
                    dependencies: new CacheDependency(null, new[] { rootCacheKey }),
                    absoluteExpiration: DateTime.Now.AddMinutes(durationMinutes),
                    slidingExpiration: Cache.NoSlidingExpiration,
                    priority: priority,
                    onRemoveCallback: null);

            return (TResult)result;
        }

        /// <summary>
        /// Call this method in `public override int SaveChanges()` of your DbContext class 
        /// to Invalidate Second Level Cache automatically.
        /// </summary>        
        public static void InvalidateSecondLevelCache(this DbContext ctx)
        {
            var changedEntityNames = ctx.ChangeTracker
                                      .Entries()
                                      .Where(x => x.State == EntityState.Added ||
                                                  x.State == EntityState.Modified ||
                                                  x.State == EntityState.Deleted)
                                      .Select(x => ObjectContext.GetObjectType(x.Entity.GetType()).FullName)
                                      .Distinct()
                                      .ToList();

            if (!changedEntityNames.Any()) return;

            printAllCachedKeys();
            foreach (var item in changedEntityNames)
            {
                item.removeEntityCache();
            }
            printAllCachedKeys();
        }
        // Private Methods (4) 

        private static void debugWriteLine(string format, params object[] args)
        {
            if (!Debugger.IsAttached) return;
            Debug.WriteLine(format, args);
        }

        private static void printAllCachedKeys()
        {
            if (!Debugger.IsAttached) return;
            debugWriteLine("Available cached keys list:");
            int count = 0;
            var enumerator = HttpRuntime.Cache.GetEnumerator();
            while (enumerator.MoveNext())
            {
                if (enumerator.Key.ToString().StartsWith("__")) continue; // such as __System.Web.WebPages.Deployment
                debugWriteLine("queryKey: {0}", enumerator.Key.ToString());
                count++;
            }
            debugWriteLine("count: {0}", count);
        }

        private static void removeEntityCache(this string rootCacheKey)
        {
            if (string.IsNullOrWhiteSpace(rootCacheKey)) return;
            debugWriteLine("Removing items with dependencyKey={0}", rootCacheKey);
            // Removes all cached items depend on this key.
            HttpRuntime.Cache.Remove(rootCacheKey);
        }

        private static void storeRootCacheKey(string rootCacheKey)
        {
            // The cacheKeys of a cacheDependency that are not already in cache ARE NOT inserted into the cache 
            // on the Insert of the item in which the dependency is used.
            if (HttpRuntime.Cache.Get(rootCacheKey) != null)
                return;

            HttpRuntime.Cache.Add(
                rootCacheKey,
                rootCacheKey,
                null,
                Cache.NoAbsoluteExpiration,
                Cache.NoSlidingExpiration,
                CacheItemPriority.Default,
                null);
        }

        #endregion Methods
    }
}

var data = context.Products.AsQueryable().Cacheable(x => x.FirstOrDefault());

using System.Data.Entity;
using EfSecondLevelCaching.Core;
using EfSecondLevelCaching.Test.Models;

namespace EfSecondLevelCaching.Test.DataLayer
{
    public class ProductContext : DbContext
    {
        public DbSet<Product> Products { get; set; }

        public override int SaveChanges()
        {
            this.InvalidateSecondLevelCache();
            return base.SaveChanges();
        }        
    }
}

using System.Data.Entity;
using System.Linq;
using EfSecondLevelCaching.Core;
using EfSecondLevelCaching.Test.DataLayer;
using EfSecondLevelCaching.Test.Models;
using System;

namespace EfSecondLevelCaching
{
    public static class TestUsages
    {
        public static void RunQueries()
        {
            using (ProductContext context = new ProductContext())
            {
                var isActive = true;
                var name = "Product1";

                // reading from db
                var list1 = context.Products
                                   .OrderBy(one => one.ProductNumber)
                                   .Where(x => x.IsActive == isActive && x.ProductName == name)
                                   .ToCacheableList();

                // reading from cache
                var list2 = context.Products
                                   .OrderBy(one => one.ProductNumber)
                                   .Where(x => x.IsActive == isActive && x.ProductName == name)
                                   .ToCacheableList();

                // reading from cache
                var list3 = context.Products
                                   .OrderBy(one => one.ProductNumber)
                                   .Where(x => x.IsActive == isActive && x.ProductName == name)
                                   .ToCacheableList();

                // reading from db
                var list4 = context.Products
                                   .OrderBy(one => one.ProductNumber)
                                   .Where(x => x.IsActive == isActive && x.ProductName == "Product2")
                                   .ToCacheableList();
            }

            // removes products cache
            using (ProductContext context = new ProductContext())
            {
                var p = new Product()
                {
                    IsActive = false,
                    ProductName = "P4",
                    ProductNumber = "004"
                };
                context.Products.Add(p);
                context.SaveChanges();
            }

            using (ProductContext context = new ProductContext())
            {
                var data = context.Products.AsQueryable().Cacheable(x => x.FirstOrDefault());
                var data2 = context.Products.AsQueryable().Cacheable(x => x.FirstOrDefault());
                context.SaveChanges();
            }
        }
    }
}

Adding new data: queryKey=72AF5DA1BA9B91E24DCCF83E88AD1C5F, dependencyKey=EfSecondLevelCaching.Test.Models.Product

Available cached keys list:
queryKey: EfSecondLevelCaching.Test.Models.Product
queryKey: 72AF5DA1BA9B91E24DCCF83E88AD1C5F
count: 2

Fetching object 'EfSecondLevelCaching.Test.Models.Product__72AF5DA1BA9B91E24DCCF83E88AD1C5F' from the cache.

Available cached keys list:
queryKey: EfSecondLevelCaching.Test.Models.Product
queryKey: 72AF5DA1BA9B91E24DCCF83E88AD1C5F
count: 2

Fetching object 'EfSecondLevelCaching.Test.Models.Product__72AF5DA1BA9B91E24DCCF83E88AD1C5F' from the cache.

Available cached keys list:
queryKey: EfSecondLevelCaching.Test.Models.Product
queryKey: 72AF5DA1BA9B91E24DCCF83E88AD1C5F
count: 2

Adding new data: queryKey=11A2C33F9AD7821A0A31003BFF1DF886, dependencyKey=EfSecondLevelCaching.Test.Models.Product

Available cached keys list:
queryKey: 72AF5DA1BA9B91E24DCCF83E88AD1C5F
queryKey: 11A2C33F9AD7821A0A31003BFF1DF886
queryKey: EfSecondLevelCaching.Test.Models.Product
count: 3

Removing items with dependencyKey=EfSecondLevelCaching.Test.Models.Product
Available cached keys list:
count: 0
Available cached keys list:
count: 0

Adding new data: queryKey=02E6FE403B461E45C5508684156C1D10, dependencyKey=EfSecondLevelCaching.Test.Models.Product

Available cached keys list:
queryKey: 02E6FE403B461E45C5508684156C1D10
queryKey: EfSecondLevelCaching.Test.Models.Product
count: 2


Fetching object 'EfSecondLevelCaching.Test.Models.Product__02E6FE403B461E45C5508684156C1D10' from the cache.

select '0.4400' as Expected , cast(0.4400 as decimal) as Actual
select '1.3200' as Expected, cast(1.3200 as decimal) as Actual
select '1.7600' as Expected, cast(1.7600 as decimal) as Actual
select '65.0000' as Expected, cast(65.0000 as decimal) as Actual
select '99.50' as Expected, cast(99.50 as decimal) as Actual

 select iif(cast(0.1 + 0.2 as decimal) = 0, 'true', 'false')

modelBuilder.Properties<decimal>().Configure(x => x.HasPrecision(18, 6));

No store type was specified for the decimal property 'Price' on entity type 'Product'.
This will cause values to be silently truncated if they do not fit in the default precision and scale.
Explicitly specify the SQL server column type that can accommodate all the values in 'OnModelCreating'
using 'HasColumnType', specify precision and scale using 'HasPrecision',
or configure a value converter using 'HasConversion'.

protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
{
    configurationBuilder.Properties<decimal>().HavePrecision(18, 6);
}

namespace CS11Tests;

public class StaticAbstractMembers
{
    public static void Test()
    {
        var sum = AddAll(new[] { 1, 2, 3, 4 });
        Console.WriteLine(sum);
    }

    private static int AddAll(int[] values)
    {
        int result = 0;
        foreach (var value in values)
        {
            result += value;
        }
        return result;
    }
}

var sum = AddAll(new[] { 1, 2, 3, 4, 0.68 });

Argument 1: cannot convert from 'double[]' to 'int[]' [CS11Tests]csharp(CS1503)

private static T AddAll<T>(T[] values)
    {
        T result = 0;
        foreach (var value in values)
        {
            result += value;
        }
        return result;
    }

T result = T.Zero;

using System.Numerics;

namespace CS11Tests;

public class StaticAbstractMembers
{
    public static void Test()
    {
        //var sum = AddAll(new[] { 1, 2, 3, 4 });
        var sum = AddAll(new[] { 1, 2, 3, 4, 0.68 });
        Console.WriteLine(sum);
    }

    private static T AddAll<T>(T[] values) where T : INumber<T>
    {
        T result = T.Zero;
        foreach (var value in values)
        {
            result += value;
        }
        return result;
    }
}

abstract static TSelf One { get; }
abstract static TSelf Zero { get; }

abstract static TResult operator +(TSelf left, TOther right);

public interface ISport
{
    bool IsTeamSport();
}

public class Swimming : ISport
{
    public bool IsTeamSport() => false;
}

public class Football : ISport
{
    public bool IsTeamSport() => true;
}

public class StaticAbstractMembers
{
    public static void Display<T>(T sport) where T : ISport
    {
        Console.WriteLine("Is Team Sport:" + sport.IsTeamSport());
    }
}

Display(new Football());

public interface ISport
{
    static abstract bool IsTeamSport();
}

public class Swimming : ISport
{
    public static bool IsTeamSport() => false;
}

public class Football : ISport
{
    public static bool IsTeamSport() => true;
}

public class StaticAbstractMembers
{
    public static void Display<T>() where T : ISport
    {
        Console.WriteLine("Is Team Sport:" + T.IsTeamSport());
    }
}

var blogs = from blog in Blogs
   where blog.Name.Contains("Development")
   select blog;

var blogs = from blog in Blogs
   where blog.Name.ComputeHash() == 0
   select blog;

public class Blog
{
   public int BlogId { get; set; }
   public string Url { get; set; }  
}

    public static class StringExtensions
    {
        public static int ComputeHash(this string str)
        {
            var hash = 0;
            foreach (var ch in str)
            {
                hash += (int)ch;
            }
            return hash;
        }
    }

using (var context = new BloggingContext())
{
   var blogs = context.Blogs
     .Where(blog => blog.Url.ComputeHash() >= 10)
     .ToList();
   Console.WriteLine(blogs.First().Url);
}

SELECT [blog].[BlogId], [blog].[Url]
   FROM [Blogs] AS [blog]

var idUrls = context.Blogs
   .Select(b => new
   {
      IdUrlString = string.Join(", ", b.BlogId, b.Url),
   }).ToList();

    public class BloggingContext : DbContext
    {
        public BloggingContext()
        { }

        public BloggingContext(DbContextOptions options)
            : base(options)
        { }

        public DbSet<Blog> Blogs { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                optionsBuilder.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Demo.ClientSideEvaluation;Trusted_Connection=True;");
                optionsBuilder.ConfigureWarnings(warnings =>
                {
                    warnings.Log(CoreEventId.IncludeIgnoredWarning);
                    warnings.Log(RelationalEventId.QueryClientEvaluationWarning);
                });
            }
        }
    }

 warn: Microsoft.EntityFrameworkCore.Query[200500]
The LINQ expression 'where ([blog].Url.ComputeHash() >= 10)' could not be translated and will be evaluated locally.

var idUrls2 = context.Blogs
   .Select(b => new
   {
     IdUrlString = b.BlogId + "," + b.Url
   }).ToList();

SELECT (CAST([b].[BlogId] AS nvarchar(max)) + N',') + [b].[Url] AS [IdUrlString]
FROM [Blogs] AS [b]

var blogs = context.Blogs
    .FromSql("SELECT * FROM dbo.Blogs")
    .ToList();

var blogs = context.Blogs
  .FromSql("EXECUTE dbo.GetMostPopularBlogs")
  .ToList();

var user = "johndoe";

var blogs = context.Blogs
  .FromSql("EXECUTE dbo.GetMostPopularBlogsForUser {0}", user)
  .ToList();

var user = new SqlParameter("user", "johndoe");
var blogs = context.Blogs
  .FromSql("EXECUTE dbo.GetMostPopularBlogsForUser @user", user)
  .ToList();

 var results = _context.Contacts.FromSql(
@"SELECT Id, Name Address, City, State, Zip 
    FROM Contacts 
    WHERE Name IN (@p0, @p1)", name1, name2);

var nameParameter = new SqlParameter
{
  ParameterName = "@name",
  Value = "doc",
  Direction = ParameterDirection.Input,
  SqlDbType = SqlDbType.NVarChar
};

var posts = context.Posts
  .FromSql("SELECT * FROM dbo.GetMatchingPostByTitle({0})", searchTerm)
  .Where(p => p.BlogId == 1)
  .OrderByDescending(p => p.CreateDate)
  .ToList();

var searchTerm = ".NET";
var blogs = context.Blogs
  .FromSql("SELECT * FROM dbo.SearchBlogs {0}", searchTerm)
  .Include(b => b.Posts)
  .ToList();

  context.Database.ExecuteSqlCommand("UPDATE dbo.People SET FirstName = 'Jane' WHERE PersonId = 30");

context.Database.ExecuteSqlCommand("usp_CreateShipper @p0, @p1",
  parameters: new[] { "hello", "world" });

using (var connection = context.Database.GetDbConnection())
{
    connection.Open();
 
    using (var command = connection.CreateCommand())
    {
        command.CommandText = "SELECT COUNT(*) FROM Contacts";
        var result = command.ExecuteScalar().ToString();
    }
}