C# If Else Statement (including Ternary Operator)

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Testing a condition is inevitable in programming. We will often face situations where we need to test conditions (whether it is true or false) to control the flow of the program. These conditions may be affected by the user's input, the time factor, the current environment where the program is running, etc.

In C# program execution flow control by the statement of control. If...else condition program first checks the condition if the condition true, then the compiler will execute the block code otherwise it will move toward the else statement.

An if statement identifies which statement to run based on the value of a Boolean expression. In the following example, the bool variable condition is set to true and then checked in the if statement. The output is that the variable is about to true.

if (boolean - expression)
 {
     // statements executed if boolean-expression is true
 }

The boolean-expression will return either true or false.

  • If the boolean-expression returns true, the statements inside the body of IF ( inside {...} ) will be executed.
  • If the boolean-expression returns false, the statements inside the body of IF will be ignored.
bool condition = true;
if (condition)
{
	Console.WriteLine("true.");
}

Output:

true.

See another example with an integer type variable

int number = 10;
if (number== 10)
{
	Console.WriteLine("you are in if statement");
}

Output:

you are in if statement

If-else statement

The if statement in C# may have an optional else statement. The block of code inside the else statement will be executed if the expression is evaluated to false.

The syntax of the if-else statement in C# is:

if (boolean - expression)
 {
         // statements executed if boolean-expression is true
 }
 else
 {
         // statements executed if boolean-expression is false
 }

The fоrmаt оf the if-else struсture соnsists оf the reserved wоrd if, Bооleаn exрressiоn, bоdy оf а соnditiоnаl stаtement, reserved wоrd else аnd else-bоdy stаtement. The bоdy оf else-struсture mаy соnsist оf оne оr mоre орerаtоrs, enсlоsed in сurly brасkets, sаme аs the bоdy оf а соnditiоnаl stаtement.

Example:

int condition = 100;
if (condition == 10)
{
	Console.WriteLine("you are in if statement");
}
else if (condition == 15)
{
	Console.WriteLine("you are else if statement");
}
else
{
	Console.WriteLine("you are in else statement");
}

Output:

you are in else statement

Nested If

Sometimes the рrоgrаmming logic in а рrоgrаmming or an аррliсаtiоn needs to be represented by multiple if-structures соntаined in eасh оther. We саll them nested if or nested if-else structures.

Example:

int condition = 100;
if (condition == 100)
{
	if (condition > 100)
	{
		Console.WriteLine("you are in if statement");
	}
	else
	{
		Console.WriteLine("you are in else statement");
	}
}
else if (condition == 15)
{
	Console.WriteLine("you are else if statement");
}
else
{
	Console.WriteLine("you are in else1 statement");
}

Output:

you are in else statement

Ternary Operator

The ternary operator is also known as a short hand if-else statement

Example:

using System;
namespace EntryPoint
{  
    class Program
    {
       //Ternary operator
       static unsafe void Main(string[] args)
        {
            int number = 100;
            string result = (number < 90) ? "if statement" : "else statement";
            Console.WriteLine(result);
        }
    }
}

Output:

else statement
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