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csharp

CSharp, also known as C#, is a programming language created by Microsoft. It runs on the .NET framework. C# is used to create web applications, desktop applications, mobile apps, and much more.

The C# Data Types Part 2 - Int
Software development

The C# data types part 2 – int

by Kenji Elzerman
written by Kenji Elzerman

C# has a lot of data types and some aren’t even used. We often use them without really knowing why we use them and what the data types are capable of. In the series “The C# data types”, I show you a few of those data types and look into them. Some basic examples, tips, and tricks. In this article: what is an int?

What is an int?

An int is declared by using the int data type, followed by the name of the variable. An int has a default value of 0 (zero).

An int (integer) can only contain whole numbers, so no decimals. The highest number an int can have is 2,147,483,647 and the lowest is -2,147,483,647. If you need a higher number you can use the long.

The System.Int32 and int are the same, where int is an alias of the System.Int32.

You can use integers to perform some calculations, like the example below.

C#
				int firstNumber = 4;
int secondNumber = 9;
int outcome = firstNumber + secondNumber; // Gives 13

Integers are not only used to calculate but they can also be used in enums and identifiers (IDs).

C#
				// Enum with identifiers
public enum Course
{
    Unknown = 0,
    Starter = 1,
    Main = 2,
    Desert = 3
}

// Enum without identifiers, numbers are still the same
public enum Course
{
    Unknown,
    Starter,
    Main,
    Desert
}

Parsing

There are several ways of parsing the int, meaning you can change the type of a string to an int, for example. You can only do this when the string contains numbers. If it contains a letter it will throw an exception. Below are the most common ways to parse an int.

int.Parse()

C#
				string a = "1234";
int b = int.Parse(a);

This code will change the string ‘a’ to an int of 1234. You can’t do math with a string, but you can with an int.

If the string a would be something like 123a4, line number 2 would give an example:

To avoid this exception or avoid handling any exception when parsing an int it’s better to use the TryParse().

int.TryParse()

C#
				string example = "1234";
int outcome;
bool isNumber = int.TryParse(example, out outcome);

if (isNumber)
    Console.WriteLine($"The total should be {outcome + 5} 1239");
else
    Console.WriteLine("Variable example is not a number");

On line 3 the int.TryParse is used. It has two parameters:

  • string a
  •  out int result
The first one is the string we want to change into an int. The second is where the changed int will be stored. The TryParse() returns a boolean. This will be true if the conversation is successful and false if it failed. In the code above the conversation will succeed. The code below will not.
C#
				string example = "123a4";
int outcome;
bool isNumber = int.TryParse(example, out outcome);

if (isNumber)
    Console.WriteLine($"The total should be {outcome + 5} 1239");
else
    Console.WriteLine("Variable example is not a number");

Convert.ToInt32()

This method can convert a string to an int. It works basically the same as the methods above and the outcome is the same.

C#
				string a = "2022";
int year = Convert.ToInt32(a);

If the string is a not a number, a FormatException will be thrown.

So, which one?

All three methods work and can convert a string to an int. But it depends on your situation. When you know the string will always be a number, no doubt about it, you can use int.Parse(). 

If you are handling user input and expect an integer, but the user can also enter other characters, use int.TryParse().

Convert.ToInt32() is a bit slower than int.TryParse() and it doesn’t give a null ArgumentNullException, whereas the others do give it when the value is NULL. The Convert class can do much more than just convert a string to an int.

Math

The int(eger) is very useful for maths, the one thing most of us hated back at school. Subtraction, adding, multiplication and division… It’s all possible. Just keep in mind that the outcome will have whole numbers only.

Basic math examples

C#
				int firstNumber = 5;
int secondNumber = 6;

int adding = firstNumber + secondNumber; // Will give 11
int substraction = firstNumber - secondNumber; // Will give -1
int multiplication = firstNumber * secondNumber; // Will give 30
int division = firstNumber / secondNumber; // Will give 0 (but is actually 0,8333333333)

Divide by zero

You can’t divide a number by zero. Not in C#, nor in a calculator. If you do this in C# you will get the exception DivideByZeroException.

C#
				// Gives compile error; application won't run.
int exampleOne = 6 / 0; 

int firstNumber = 5;
int secondNumber = 0;

// Crashes when run and gives a DivideByZeroException exception
int adding = firstNumber / secondNumber;

Line 2 will give a compile error. This means Visual Studio will show a red curly line under the “6 / 0”. It’s smart enough to recognize the error.

Line 8 however won’t see the ‘error’ and you can run the application. The application will crash when reaching line 8 and give the exception.

Rounding up or down

In a previous example I showed that 5 / 6 is zero, but it’s actually 0,833333. In most case this number will be rounded up, making it 1. In C# this can be done with Math.Round().

The Math.Round() can round a number up or down. In this case, with the 5 / 6 we don’t have to do anything. The Math.Round() will see it’s above 0.5 and rounds it up. Two downsides… First, we need to convert one of the two variables to a decimal. It’s not hard, but not really nice. Second is that the Math.Round() returns a decimal, but we want to use int. Again, not hard, but not nice.

C#
				int firstNumber = 5;
int secondNumber = 6;

int result = (int)Math.Round(firstNumber / (decimal)secondNumber);

Validation

An int is by default 0 (zero) and it can only contain whole numbers, negative or positive. Validating an int is fairly easy. Usually, you check if an int is smaller, bigger, equal, or a combination of these.

C#
				int a = 1;

if (a == 0)
    Console.WriteLine($"A is zero");

if (a > 1)
    Console.WriteLine("A is larger than one");

if (a < 1)
    Console.WriteLine("A is smaller than one");

if (a != 1)
    Console.WriteLine("A is not one");

if (a >= 1)
    Console.WriteLine("A is larger or equal than one");

if (a <= 1)
    Console.WriteLine("A is larger or equal than one");

An int is not nullable, meaning you can’t assign NULL to it. But you can make it nullable by adding the question mark(?) after int. This is not something I would advise.

C#
				int? a = 1;

if (a.HasValue && a.Value > 1)
    Console.WriteLine("A is not NULL and larger than one");

Conclusion for integers

I think that int is just as important as the string. You can use it anywhere and you will be using it everywhere. From simple math calculations to identifiers to enumerations. The only downside for int is that it can only contain whole numbers, so no decimals. For these, you will need to use other data types.

If you want to read more about the int and numbers, you can read the official Microsoft page.

If you think some method or trick is missing, let me know!

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The C# Data Types Part 1 - String
Software development

The C# data types part 1 – string

by Kenji Elzerman
written by Kenji Elzerman

C# has a lot of data types and some aren’t even used. We often use them without really knowing why we use them and what the data types are capable of. In the series “The C# data types”, I show you a few of those data types and look into them. Some basic examples, tips, and tricks. In this article: string.

The String

A string is the most commonly used data type in C# and other languages. It’s used to contain text and text is all the characters you can imagine. 

Basic usage

A string is usually initialized with the text surrounded by quotes. It’s also possible to initialize it with NULL.

C#
				string message = "Hello world"; // Initialize string with text
string message2 = null; // Initialize string with null

string message3 = "You can also put numbers in a string: 12345. Or other chars #$(!&"; 

string number1 = "1";
string number2 = "2";
string totalNumber = number1 + number2; // This is not 3, but it's 12

String vs System.String

There are two string keywords. One is the string (lower s) and String (capital s). The second is the class, used for accessing certain static methods. You can use the String for declaring variables and adding values to them, but you will need to add a using to System. With the string (lower s) you don’t need to add any usings.

But in the end, there isn’t much difference between both strings. The string is an alias for System.String, so it has all the functionalities of the System.String. The latter is used for static methods like Format, IsNullOrEmpty, IsNullOrWhitespace, ToLower, ToUpper, and more.

Common string actions

Concatenate

A way to combine two or more strings into one string. There are several tricks of doing this.

C#
				string first = "This is the first."; 
string second = "This is the second."; 

string total = first + second; // Using the + operator
string total2 = $"{first}{second}"; // String interpolation
first += second; // Using the += operator
string total3 = String.Format("{0}{1}", first, second); // Using the String.Format()

While the above examples are all correct and working, string interpolation and the += operator are proven to have the best performance. It really depends on what you try to achieve in your code.

ToLower and ToUpper

Two methods that are very valuable when doing checks. If you want to check if value 1 has the same content as value 2 it’s best to convert all characters to lower cases or upper cases. 

C#
				string first = "AbcdEfg"; 
string second = "abcdefg"; 

if(first == second) // This is false
    Console.WriteLine("Yes! They are the same");

if(first.ToLower() == second.ToLower()) // This is true
    Console.WriteLine("Yes! They are the same");

Length

A read-only property that returns the number of characters of the string. You can’t set the length.

C#
				string text = "Hello world";

Console.WriteLine(text.Length); // Will show 11

StringBuilder

A StringBuilder is used to easily hold and concatenate strings. It works a bit like a list, but it has different methods. You can add text or lines to the StringBuilder. When you are done you can convert the StringBuilder to a string.

C#
				using System.Text;

StringBuilder sb = new();
sb.Append("Add text to the StringBuilder");
sb.AppendLine("This text will be placed directly after the previous append, but the next append(line) will be on a new line.");
sb.AppendLine("Append line will add a new line to the string builder.");

string totalText = sb.ToString();

Console.WriteLine(totalText);

The result:

ToString

Maybe the most used function for a string. ToString converts almost everything to a string. For example an integer:

C#
				int year = 2021;
string stringYear = year.ToString();

If you try to add 1 to the stringYear you will get “20211”, not 2022, which is the case if you add 1 on the year variable.

If you use ToString on classes that don’t have the ToString implemented or overridden it will return the full name of the class, including the namespace.

C#
				using Some.Other.NameSpace;

Movie movie = new()
{
    Title = "The Matrix",
    Rating = 5
};

Console.WriteLine(movie.ToString()); // This will show Some.Other.Namespace.Movie

namespace Some.Other.NameSpace
{
    public class Movie
    {
        public string Title { get; set; }
        public int Rating { get; set; }

        public void SetRating(int rating)
        {
            Rating = rating;
        }
    }
}

But if we would override the ToString on the Movie class it could look like this:

C#
				using Some.Other.NameSpace;

Movie movie = new()
{
    Title = "The Matrix",
    Rating = 5
};

Console.WriteLine(movie.ToString());

namespace Some.Other.NameSpace
{
    public class Movie
    {
        public string Title { get; set; }
        public int Rating { get; set; }

        public void SetRating(int rating)
        {
            Rating = rating;
        }

        public override string ToString()
        {
            return $"{Title} has a rating of {Rating}";
        }
    }
}

PadLeft and PadRight

These two will add whitespaces in front (PadLeft) or behind (PadRight) of the string. A good way to align text in a console application for example.

C#
				string text = "Hello world";
string secondText = "Bye!";

Console.WriteLine(text);
Console.WriteLine(secondText.PadLeft(11));

Replace

Replace is a wonderful method to replace a certain part of the contents of the string. The method Replace will create a new string and replaces all occurrences with the new value.

C#
				string thisShouldBeMadeUrlFriend = "Hello world! #DefaultText";

string urlText = thisShouldBeMadeUrlFriend
    .Replace("!", string.Empty)
    .Replace("#", string.Empty)
    .Replace("_", string.Empty)
    .Replace("Hello", "Goodbye")
    .ToLower();

// Will result in goodbye_world_defaulttext

SubString

The SubString lets you grab a specific part of the content of the string. It works with positions (int). 

C#
				string exampleText = "Hello world! #DefaultText";

// Only get the first 5 characters from the beginning
string substring1 = exampleText.Substring(5); // Will return " world! #DefaultText" 

// Start a position, get until position 5
string substring2 = exampleText.Substring(6, 5); // Will return "world" 

// Get the word "DefaulText" only.
// Not the most elegant way, but showing you the possibilities.
string substring3 = exampleText.Substring(exampleText.Length - "#DefaultText".Length + 1, "DefaultText".Length); // Will return "DefaultText"

Split

This literally splits the string into pieces, placing the pieces in an array. Ideally to real URL segments or other strings where you need that one, little piece of text.

The Split() gets one parameter, which is the char on which the string should be split.

C#
				string exampleText = "https://kenslearningcurve.com/tutorials/the-minimal-api-with-net-6/";

string[] elements = exampleText.Split("/");

string category = elements[3]; // This will be 'tutorials'

Trim

The Trim-method will remove empty spaces at the front and back of a string. Perfect for cleaning up user input.

C#
				string exampleText = " UserEmail@someemail.com "; // This has spaces in the front and back of the e-mail.

Console.WriteLine(exampleText.Trim()); // Will show the same e-mail, but without the spaces.

Trim removes spaces on both sides, not in between. If you want to remove spaces at the front, use TrimStart(). TrimEnd() will remove spaces at the end of the string.

If you want to remove spaces in the middle of a string, use Replace().

Validations

It’s pretty common to check the contents of a string. Whether it has a certain value or if it’s empty, most validations are easy to do.

String.IsNullOrEmpy

Checks if the string, parameter, is null or empty.

C#
				string text = "";

if (string.IsNullOrEmpty(text))
    Console.WriteLine("Correct");
else
    Console.WriteLine("String is not null or empty.");

text = string.Empty;

if (string.IsNullOrEmpty(text))
    Console.WriteLine("Correct");
else
    Console.WriteLine("String is not null or empty.");

text = null;

if (string.IsNullOrEmpty(text))
    Console.WriteLine("Correct");
else
    Console.WriteLine("String is not null or empty.");

text = "Hello world";

if (string.IsNullOrEmpty(text))
    Console.WriteLine("Correct");
else
    Console.WriteLine("String is not null or empty.");

Contains

A function that returns true if a string contains a specific set of one or more characters.

C#
				string text = "Hello world";

if (text.Contains("or"))
    Console.WriteLine("Yes, it contains 'or'");

To avoid problems with uppercase and lowercase characters it is wise to use the StringComparison option. This will allow you to choose whether you want to ignore uppercase characters or not.

C#
				string text = "Hello wOrld"; // Note the capital O!

if (text.Contains("or")) // Is false
    Console.WriteLine("Yes, it contains 'or'");
else
    Console.WriteLine("There is no 'or' in the text.");

if (text.Contains("or", StringComparison.CurrentCultureIgnoreCase)) // Is true
    Console.WriteLine("Yes, it contains 'or'");
else
    Console.WriteLine("There is no 'or' in the text.");

StartsWith and EndsWith

These two determine if a string starts or ends with a specific value. This way you can check whether you want to handle a specific string or not.

C#
				string exampleText = "https://kenslearningcurve.com/about-me/";

if (exampleText.StartsWith("https"))
    Console.WriteLine("This URL starts with HTTPS and is safe.");

if (exampleText.EndsWith("/aboutme"))
    Console.WriteLine("This is my personal page. Always show it, whether it is HTTP or not.");

Conslusion for string

The string is a powerful data type that we all use. It’s especially easy when using and handling text since the string can hold all the characters we have.

Putting all the methods and functions of the string on this page is impossible and written down many times by others. This article contains the methods and functions most used. If you want to have a full view of this data type, check out the Microsoft documentation for more.

If you think some method or trick is missing, let me know!

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