C# if-else

In C# programming, the if statement is used to test the condition. There are various types of if statements in C#.

if statement
if-else statement
nested if statement
if-else-if ladder

C# IF Statement

The C# if statement tests the condition. It is executed if condition is true.
Syntax:

if(condition){
//code to be executed
}

C# If Example

using System;
public class IfExample
{
public static void Main(string[] args)
{
int num = 10;
if (num % 2 == 0)
{
Console.WriteLine("It is even number");
}
}
}

Output:

It is even number

C# IF-else Statement

The C# if-else statement also tests the condition. It executes the if block if condition is true otherwise else block is executed.
Syntax:

if(condition){
//code if condition is true
}else{
//code if condition is false
}

C# If-else Example

using System;
public class IfExample
{
public static void Main(string[] args)
{
int num = 11;
if (num % 2 == 0)
{
Console.WriteLine("It is even number");
}
else
{
Console.WriteLine("It is odd number");
}
}
}

Output:

It is odd number

C# If-else Example: with input from user

In this example, we are getting input from the user using Console.ReadLine() method. It returns string. For numeric value, you need to convert it into int using Convert.ToInt32() method.

using System;
public class IfExample
{
public static void Main(string[] args)
{
Console.WriteLine("Enter a number:");
int num = Convert.ToInt32(Console.ReadLine());
if (num % 2 == 0)
{
Console.WriteLine("It is even number");
}
else
{
Console.WriteLine("It is odd number");
}
}
}

Output:

Enter a number:11
It is odd number

Output:

Enter a number:12
It is even number

C# IF-else-if ladder Statement

The C# if-else-if ladder statement executes one condition from multiple statements.
Syntax:

if(condition1){
//code to be executed if condition1 is true
}else if(condition2){
//code to be executed if condition2 is true
}
else if(condition3){
//code to be executed if condition3 is true
}
...
else{
//code to be executed if all the conditions are false
}

C# If else-if Example

using System;
public class IfExample
{
public static void Main(string[] args)
{
Console.WriteLine("Enter a number to check grade:");
int num = Convert.ToInt32(Console.ReadLine());
if (num <0 || num >100)
{
Console.WriteLine("wrong number");
}
else if(num >= 0 && num < 50){
Console.WriteLine("Fail");
}
else if (num >= 50 && num < 60)
{
Console.WriteLine("D Grade");
}
else if (num >= 60 && num < 70)
{
Console.WriteLine("C Grade");
}
else if (num >= 70 && num < 80)
{
Console.WriteLine("B Grade");
}
else if (num >= 80 && num < 90)
{
Console.WriteLine("A Grade");
}
else if (num >= 90 && num <= 100)
{
Console.WriteLine("A+ Grade");
}
}
}

Output:

Enter a number to check grade:66
C Grade

Output:

Enter a number to check grade:-2
wrong number

An operator is used to perform some operation eithor mathematical or logical on operands. C# provides following Operators.

Arithmetic Operators
Relational Operators
Logical Operators
Assignment Operators
Misc Operators

1. Relational Operators

Following tables shows the operators and its working with examples.

Operator	Description	Example
==	Checks if the values of two operands are equal or not, if yes then condition becomes true.	(A == B) is not true.
!=	Checks if the values of two operands are equal or not, if values are not equal then condition becomes true.	(A != B) is true.
>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	(A > B) is not true.
<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	(A < B) is true.
>=	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	(A >= B) is not true.
<=	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	(A <= B) is true.

2. Arithmetic Operators

Operator	Description	Example
+	Adds two values	A + B = 30
-	Subtracts second values from the first values	A - B = -10
*	Multiplies two or more values	A * B = 200
/	Divides numerator by de-numerator	B / A = 2
%	Modulus Operator and remainder of after an integer division	B % A = 0
++	Increment operator increases integer value by one	A++ = 11
--	Decrement operator decreases integer value by one	A-- = 9

3. Logical Operators

Operator	Description	Example
&&	Called Logical AND operator. If both the operands are non zero then condition becomes true.	(A && B) is false.
\|\|	Called Logical OR Operator. If any of the two operands is non zero then condition becomes true.	(A \|\| B) is true.
!	Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	!(A && B) is true.

4. Assignment Operator

Operator	Description	Example
=	Simple assignment operator, Assigns values from right side operands to left side operand	C = A + B assigns value of A + B into C
+=	Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand	C += A is equivalent to C = C + A
-=	Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand	C -= A is equivalent to C = C - A
*=	Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand	C = A is equivalent to C = C A
/=	Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand	C /= A is equivalent to C = C / A
%=	Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand	C %= A is equivalent to C = C % A
<<=	Left shift AND assignment operator	C <<= 2 is same as C = C << 2
>>=	Right shift AND assignment operator	C >>= 2 is same as C = C >> 2
&=	Bitwise AND assignment operator	C &= 2 is same as C = C & 2
^=	bitwise exclusive OR and assignment operator	C ^= 2 is same as C = C ^ 2
\|=	bitwise inclusive OR and assignment operator	C \|= 2 is same as C = C \| 2

5. Misc Operators

Operator	Description	Example
sizeof()	Returns the size of a data type.	sizeof(int), returns 4.
typeof()	Returns the type of a class.	typeof(StreamReader);
&	Returns the address of an variable.	&a; returns actual address of the variable.
*	Pointer to a variable.	*a; creates pointer named 'a' to a variable.
? :	Conditional Expression	If Condition is true ? Then value X : Otherwise value Y
is	Determines whether an object is of a certain type.	If( Ford is Car) // checks if Ford is an object of the Car class.
as	Cast without raising an exception if the cast fails.	Object obj = new StringReader("Hello"); StringReader r = obj as StringReader;

C# Control Statements (if-else)

C# if-else

C# IF Statement

C# If Example

C# IF-else Statement

C# If-else Example

C# If-else Example: with input from user

C# IF-else-if ladder Statement

C# Operators

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