How to pass any number of parameters into a method in C# .NET

April 8, 2015 1 Comment

You must have come across built-in methods in .NET where you can send any number of arguments into a method. E.g. string.Format has an overload where you can pass in a format string and then an array with the “params” modifier.

There’s nothing stopping you from using the same keyword to write a similar method, here’s an example:

public void MethodWithParams(int toBeMultiplied, params int[] multipliers)
{
	foreach (int m in multipliers)
	{ 
		Console.WriteLine(string.Format("{0} x {1} = {2}", toBeMultiplied, m, toBeMultiplied * m));
	}
}

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Implementing an indexer for your object with C# .NET

April 7, 2015 1 Comment

Indexers are used extensively when accessing items in an array or List:

Friend f = friends[2];

It’s fairly easy to implement your own indexer. Imagine a table with guests sitting around. We could implement an indexer to easily access guest #n.

The Guest object is simple with only one property:

public class Guest
{
	public string Name { get; set; }
}

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Using Amazon RedShift with the AWS .NET API Part 7: data warehousing and the star schema

April 5, 2015 1 Comment

Introduction

In the previous post we dived into Postgresql statement execution on a RedShift cluster using C# and ODBC. We saw how to execute a single statement or many of them at once. We also tested a parameterised query which can protect us from SQL injections.

In this post we’ll deviate from .NET a little and concentrate on the basics of data warehousing and data mining in RedShift. In particular we’ll learn about a popular schema type often used in conjunction with data mining: the star schema.

Star and snowflake schemas

I went through the basic characteristics of star and snowflake schemas elsewhere on this blog, I’ll copy the relevant parts here.

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Creating temporary files on Windows using C# .NET

April 3, 2015 3 Comments

It’s trivial to create a temporary file using the Path class in .NET. Let’s first see how to find the path to the current user’s temp folder:

string tempFolderPath = Path.GetTempPath();

In my case it returns C:\Users\andras.nemes\AppData\Local\Temp\ which is the same as the value of the TEMP environment variable at the user level on my PC.

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Using Amazon RedShift with the AWS .NET API Part 6: Postgresql to master node using ODBC

April 2, 2015 3 Comments

Introduction

In the previous post we tested how to connect to the master node in code using the .NET AWS SDK and ODBC. We also executed our first simple Postgresql remotely. In this post we’ll continue in those tracks and execute some more Postgresql statements on our master node.

Preparation

We’ll execute most of the scripts we saw in this blog post. Prepare a text file called postgresscript.txt with the following content and save it somewhere on your harddrive:

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Checking for arithmetic overflow in C# .NET

April 1, 2015 2 Comments

As you know primitive numeric types in C# – and other modern programming languages – have maximum and minimum values that can be stored in memory. If you’re trying to store a larger number in the variable then you’ll get an overflow with unexpected results.

Let’s see an example with the “byte” type. It is actually not one of the primitive types, like int or long, but simply a keyword for an integral type to store the numbers 0-255. Why 255? 1 byte consists of 8 bits and 8 bits in the computer’s memory allows us to store 255 as the highest number. 255 in binary is all 1’s for all 8 bits:

11111111

What happens if we add 1 to that? On paper we can easily solve it by some basic binary maths:

11111111
+ 00000001
===========
100000000

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How to create custom string formatters with C# .NET

March 31, 2015 1 Comment

.NET has a fairly large number of built-in string formatters that you can pass into the string.Format method. Here are some examples from the MSDN page about formatting:

String.Format("{0,-12}{1,8:yyyy}{2,12:N0}{3,8:yyyy}{4,12:N0}{5,14:P1}",
                                city.Item1, city.Item2, city.Item3, city.Item4, city.Item5,
                                (city.Item5 - city.Item3)/ (double)city.Item3);
String.Format("{0,-12}{1,8}{2,12}{1,8}{2,12}{3,14}\n",
                                    "City", "Year", "Population", "Change (%)");
String.Format("{0,-10:C}", 126347.89m);

The IFormatProvider and ICustomFormatter interfaces will provide you with the methods required to create your own formats.

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Using Amazon RedShift with the AWS .NET API Part 5: connecting to master node using ODBC

March 30, 2015 5 Comments

Introduction

In the previous post we went through some basic C# code to communicate with Amazon RedShift. We saw how to get a list of clusters, start a new cluster and terminate one using the .NET AWS SDK.

We haven’t yet seen how to execute Postgresql commands on RedShift remotely from code. That is the main goal of this post.

Installing the ODBC driver

In this section we’ll prepare our Windows environment to be able to connect to RedShift using ODBC. At times this can be a frustrating experience so I’ll try to give you as much detail as I can.

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Compose extremely large integers using BigInteger in C# .NET

March 27, 2015 1 Comment

The largest integer that can be stored in a long, i.e. a 64-bit integer is 9,223,372,036,854,775,807 in .NET. That is a very large number that will be enough for most applications out there.

However, sometimes it’s not enough and you need to handle something larger. This article on Wikipedia shows several use cases where this can occur. .NET also provides the float and double numeric types that provide much larger ranges. They won’t be integers exactly but they may suit your needs anyhow.

The .NET framework has an object called BigInteger that lets you construct arbitrarily large integers. This object resides in the System.Numerics namespace so you’ll need to reference the System.Numerics.dll library.

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Using Amazon RedShift with the AWS .NET API Part 4: code beginnings

March 26, 2015 Leave a comment

Introduction

In the previous post we looked into how to connect to the Amazon RedShift master node using a tool called WorkBenchJ. We also went through some very basic Postgresql statements and tested an equally basic aggregation script.

In this post we’ll install the .NET SDK and start building some test code.

Note that we’ll be concentrating on showing and explaining the technical code examples related to AWS. We’ll ignore software principles like SOLID and layering so that we can stay focused. It’s your responsibility to organise your code properly. There are numerous posts on this blog that take up topics related to software architecture.

Installing the SDK

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