Tag Archives: convert

Coding in C#, Video

Converting variable types in C#

This tutorial explains how to convert variable types in the C# language (eg. convert from string to integer or float, or convert from integer or float to string). Here is a summary of the methods used:

  • float.Parse() – converts to float type
  • int.Parse() – converts to int type
  • .ToString() – converts to string type

Watch the video below and then scroll down to see the sample code.

Example of converting from string to float:

float myFloatVariable = float.Parse(myStringVariable);

Example of converting from string to int:

int myIntVariable = int.Parse(myStringVariable);

Example of converting from int or float to string:

string myStringVariable = myFloatVariable.ToString();

Here is the full sample code from the tutorial video:

using System;

namespace MyCSharpProject
{
  class MainClass
  {
    public static void Main(string[] args)
    {
      Console.WriteLine("Enter your name: ");
      string username = Console.ReadLine(); // store user input as string
      Console.WriteLine("Hello there, " + username);

      Console.WriteLine("Enter two numbers");
      float num1 = float.Parse(Console.ReadLine()); // convert user input from string to float
      float num2 = float.Parse(Console.ReadLine()); // convert user input from string to float
      Console.WriteLine("The result is: " + (num1 + num2)); // display string of text and float result 

      int num3 = 5;
      int num4 = 10;
      Console.WriteLine(num3.ToString() + num4.ToString()); // convert int to string
    }
  }
}


Next tutorial: Making comparisons in C#

Video, Xamarin & C#

Integers and floats in C#

In the previous tutorial we looked at how to create variables and work with the string data type in C#. In this tutorial we will look at how to work with the integer and float data types in C# and also how to convert strings to integers or floats using the int.Parse() and float.Parse() methods. You will also learn how to manipulate numbers using arithmetic operators.

Watch the video below or scroll down to see the sample code.

Sample C# code

using System;

namespace MyCSharpApp
{
  class MainClass

  {
    public static void Main (string[] args)
    {
      Console.WriteLine ("Enter two numbers...");
      float num1 = float.Parse(Console.ReadLine ());
      float num2 = float.Parse(Console.ReadLine ());
      Console.WriteLine (num1 + num2);
    }
  }
}

Arithmetic operators

Arithmetic operators are used for performing standard math operations on variables and are usually only used number variables (although they can be used for other things too).

Operator Name / description
+ Addition – this operator is used to add two numbers together. It can also be used to concatenate (join) two strings together.
– Subtraction – this operator is used to subtract one number from another.
* Multiplication – this operator is used to multiply two numbers together.
/ Division – this operator is used to divide one number by another.
% Modulus – this operator is used to divide one number by another but instead of returning the result, it returns the remainder of the division. Eg. 5%2 would return a result of 1.

Brackets can also be used for more complex math operations eg. 5 + (10 * (6 / 3) / 2);

The assignment operators follow standard mathematic order of operations. That means that the math works from left to right. Parenthesis are done first, multiplication and division comes second, and then addition and subtraction come third.

Assignment operators

Assignment operators are used to assign a value to a variable. The most frequently used assignment operator is the equals (=) sign. There are other operators as well that are used to combine multiple operations into one. The syntax of a standard variable assignment looks like this:

<variable name> <assignment operator> <value>;

For example: x = 5;

The table below shows the different assignment operators available in C#.

Operator Description
= The equals sign is used to assign the value on the right side of the equals sign to the variable on the left side of the equals sign.
+= , -= , *= and /= These assignment operators are also used to perform arithmetic operations and assign the result to the variable eg. x *= 5 is the same as saying x = x * 5.
++ and — These assignment operators are called increment and decrement operators and are used to increase or decrease the value of a variable by 5. For example, x++ is the same as saying x = x + 1.

Next tutorial: Conditional programming in C#

ICT, Video

Converting between decimal and binary

Everything you see on this screen right now, when broken down, is in the form of binary. This is the only language that computers understand. In fact, when we code in different programming languages such as JavaScript, Python, or C#, these languages must be converted into binary in order for the different parts of the computer to understand the instructions. Everything a computer knows is represented in binary – 1 or 0 values, also known as on and off, or high and low. Binary numbers can be converted to and from the decimal number system.

The video below explains how to convert between binary and decimal number systems.

 

JavaScript, Video

Working with Strings in JavaScript

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This video tutorial explains how to concatenate (join) strings, convert between integers and strings, change text to uppercase and lowercase, and also introduces indexing and arrays.

You can watch the video below or click here to view it on YouTube.  This is the fourth video from the beginners JavaScript tutorial video series.

The sample code snippet below shows how to join (concatenate) strings, find the length of a string (the number of characters in a string), convert from integer to string, display specific characters in a string, split a string up and place each word in a separate array element, and convert string to uppercase and lowercase.

Don’t try all of this in one go. Have a go at one string operation at a time and only move on to the next one when you feel comfortable to.

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="utf-8"/>
 <title>JavaScript - Strings</title>
 <script type="text/javascript">
 
 var firstName = "Nicolas";
 var lastName = "Cage";
 
 // Concatenation means joining (eg. joining two strings together to form one string
 // Below, is an example of a concatenated string being held in a variable
 var joinednames = firstName + lastName;
 
 // Below, is an example of concatention with spaces added between words.
 document.write(firstName,' ',lastName,' ',"says \"hello\".");
 
 var fullName = firstName + ' ' + lastName; // this combines two variables and a space between the strings into a new variable
 
 document.write(fullName)
 
 var nameLength = fullName.length; // this calculates the length of the string as an integer
 document.write(nameLength);
 
 var age = 20;
 document.write(fullName + age); // this prints the name string and then the variable (no spaces) 
 
 var ageString = age.toString(); // this converts the age integer variable to a string variable
 document.write(ageString);
 
 /* To convert a string to an integer, the variable must firstly contain ony numbers. It can simply be multiplied by 1 to convert to an integer
 eg. newIntVariable = stringVariable * 1
 or you can use parseInt and parseFloat functions eg parseInt('77');
 */
 
 var message = 'Hello world!';
 document.write(message.indexOf('w')) // the indexOf function finds the index number of a character in a string
 document.write(message.charAt(8)) // this gives the character at index number 8
 document.write(message.length) // this will give the length of the string
 
 var messageArray = new Array();
 messageArray = message.split(' '); //this splits the words (where there is a space) into a new array
 document.write(messageArray[0],"</br>"); // this would return "Hello" (and a new line)
 document.write(messageArray[1]); // this would return "world!"
 
 document.write(message.substring(4,8)); //this will show anything between index number 4 and 8
 document.write(message.substr(4,8)); //substr is different to substring. this will show the 8 characters after index number 4.
 
 document.write(message.toUpperCase()); // converts string to uppercase
 document.write(message.toLowerCase()); // converts string to lowercase
 document.write("<b>",message.toUpperCase(),"</b>"); // this prints the uppercase string in bold using the HTML bold element <b>
 document.write("<h1>This is a heading</h1>"); // HTML elements can be put straight into a string
 </script>
 
</head>
<body>
 
 
</body>
</html>

Next tutorial: Events