Tips and tricks in C# .NET
January 15, 2016 Leave a comment
Let’s say you have the following three numbers:
…and you’d like to format them as follows:
There’s a special format string that can be used for this purpose. It consists of 3 parts separated by a semi-colon. The first part applies to positive numbers, the second to negative numbers and the third to zeroes:
January 13, 2016 2 Comments
How do you read the date “03-10-2014”? For some of you this will be October 03 2014. For others, especially those from the US this will be interpreted as March 10 2014. This is because dates are represented in different formats in different cultures.
Consider the following code:
string dateString = "03-10-2014"; DateTime parsedDate = DateTime.Parse(dateString); string toString = parsedDate.ToLongDateString();
January 12, 2016 1 Comment
Imagine that you’d like to be notified when something is changed in a collection, e.g. an item is added or removed. One possible solution is to use the built-in .NET generic collection type ObservableCollection of T which is located in the System.Collections.ObjectModel namespace. The ObservableCollection object has an event called CollectionChanged. You can hook up an event handler to be notified of the changes.
If you don’t know what events, event handlers and delegates mean then start here.
Let’s see a simple example with a collection of strings:
December 18, 2015 Leave a comment
It’s easy to override the mathemtical operators like + or – in C# to build custom operations.
Consider the following simple Rectangle class:
public class Rectangle
{
public Rectangle(int width, int height)
{
Height = height;
Width = width;
}
public int Width
{
get;
set;
}
public int Height
{
get;
set;
}
}
December 16, 2015 1 Comment
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
December 15, 2015 1 Comment
Custom implicit and explicit conversions for numeric types can be defined in C# quite easily. You need to be aware of the “implicit”, “explicit” and “operator” keywords.
Consider the following class:
public class Measurement
{
public int Value { get; set; }
}
December 9, 2015 Leave a comment
Imagine that you’d like to build a list type of collection where you want to restrict the insertion and/or deletion of items in some way. Let’s say we need an integer list with the following rules:
One possible solution is to derive from the Collection of T class. The generic Collection of T class in the System.Collections.ObjectModel namespace provides virtual methods that you can override in your custom collection.
The virtual InsertItem and SetItem methods are necessary to control the behaviour of the Collection.Add and the way items can be modified through an indexer:
December 8, 2015 1 Comment
Say you have a method which accepts a string parameter. The method may need to handle null values in some way. One strategy is to validate the parameter and throw an exception:
private static string Resolve(string input)
{
if (input == null) throw new ArgumentNullException("Input");
.
.
.
}
Another strategy is to provide some default value with an if-else statement:
December 2, 2015 1 Comment
In this we saw how to convert between numeric types explicitly and implicitly. There are other ways to implement conversions in C#. You must have come across the System.Convert static methods such as System.ConvertToInt32 or System.ConvertToByte.
You can implement your own conversions by implementing the IConvertible interface. Consider the following object:
public class House
{
public double Area { get; set; }
public int NumberOfRooms { get; set; }
public string Address { get; set; }
public bool ForSale { get; set; }
public DateTime DateBuilt { get; set; }
}
December 1, 2015 Leave a comment
In this post we’ll quickly go through positional vs. keyword function arguments in C#.
Say you have the following function:
public string GetContent(bool base64encode, bool compress, bool withUniqueId, string filename, int maxSize)
{
return string.Empty;
}
You’ll learn very early in your programming class that you can call a function by supplying the arguments in exactly the same order as they are listed in the method signature. Here’s an example:
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