Industrial Training

C# Type Casting

Type casting is when you assign a value of one data type to another type.

In C#, there are two types of casting:

Implicit Casting: Implicit casting is done automatically when passing a smaller size type to a larger size type
Explicit Casting: Explicit casting must be done manually by placing the type in parentheses in front of the value:

Example :

int myInt = 9;
double myDouble = myInt;       // Automatic casting: int to double
            
Console.WriteLine(myInt);      // Outputs 9
Console.WriteLine(myDouble);   // Outputs 9
        
double myDouble = 9.78;
int myInt = (int) myDouble;    // Manual casting: double to int
            
Console.WriteLine(myDouble);   // Outputs 9.78
Console.WriteLine(myInt);      // Outputs 9

It is also possible to convert data types explicitly by using built-in methods, such as Convert.ToBoolean, Convert.ToDouble, Convert.ToString, Convert.ToInt32 (int) etc.

C# User Input

We can use Console.ReadLine() to get user input.

// Type your username and press enter
Console.WriteLine("Enter username:");
    
// Create a string variable and get user input from the keyboard and store it in the variable
string userName = Console.ReadLine();
    
// Print the value of the variable (userName), which will display the input value
Console.WriteLine("Username is: " + userName);

C# Operators

Operators are used to perform operations on variables and values.

Arithmetic Operators

Arithmetic operators are used to perform common mathematical operations:

Operator	Name	Description	Example
+	Addition	Adds together two values	x + y
-	Subtraction	Subtracts one value from another	x - y
*	Multiplication	Multiplies two values	x * y
/	Division	Divides one value by another	x / y
%	Modulus	Returns the division remainder	x % y
++	Increment	Increases the value of a variable by 1	x++
--	Decrement	Decreases the value of a variable by 1	x--

Assignment Operators

Assignment operators are used to assign values to variables.

Operator	Example	Same As
=	x = 5	x = 5
+=	x += 3	x = x + 3
-=	x -= 3	x = x - 3
*=	x *= 3	x = x * 3
/=	x /= 3	x = x / 3
%=	x %= 3	x = x % 3

Comparison Operators

Comparison operators are used to compare two values:

Operator	Name	Example
==	Equal to	x == y
!=	Not equal	x != y
>	Greater than	x > y
<	Less than	x < y
>=	Greater than or equal to	x >= y
<=	Less than or equal to	x <= y

Logical Operators

Logical operators are used to determine the logic between variables or values

Operator	Name	Description	Example
&&	Logical and	Returns true if both statements are true	x < 5 && x < 10
\|\|	Logical or	Returns true if one of the statements is true	x < 5 \|\| x < 4
!	Logical not	Reverse the result, returns false if the result is true	!(x < 5 && x < 10)

C# Math

The C# Math class has many methods that allows you to perform mathematical tasks on numbers.

The Math.Max(x,y) method can be used to find the highest value of x and y
The Math.Min(x,y) method can be used to find the lowest value of of x and y
The Math.Sqrt(x) method returns the square root of x
The Math.Abs(x) method returns the absolute (positive) value of x
Math.Round() rounds a number to the nearest whole number

C# Strings

A string variable contains a collection of characters surrounded by double quotes

String Length: the length of a string can be found with the Length property
ToUpper() and ToLower() methods returns the string converted to uppercase or lowercase
String Concatenation: The + operator can be used between strings to combine them. This is called concatenation

C# Booleans

We use boolean expressions, for conditional testing

int x = 10;
int y = 9;
Console.WriteLine(x > y); // returns True, because 10 is higher than 9

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