C# - IF...ELSE

If...Else is somewhat similar to Decision Making.

Everyone has to make some kind of Decision in everyday life. Be it choosing a shirt or going to office by Bus or Cab.

Even in case of C#, it has to make Decision.

And to make a Decision, If...Else is used by C#.

There are three Decision Making statements used by C# :

else

else if

Let us see them in detail.

The if statement for Decision Making

Let us understand if statement with the below example:

Say, you have a friend, who cannot remember anything. Now, you ask him to go to the market and get 1 kg Apple. You also tell him, if the price of Apple is less than 150 bucks, only then he should buy the Apple.

And since your friend has a weak memory. He takes out his notebook and writes :

"If the price of Apple is less than 150 then buy the apples"

Now, if your friend has to write the same thing in C#. How would he write it?

Let us see with the below example.

Example :

public class MyApplication
{
    public static void Main(string[] args)
     {
        int price = 120;
	    if (price < 150) 
	    {
		    System.Console.WriteLine("Buy the apples");
	    }
    }
}

Output :

Buy the apples

So, your friend writes the same thing in C# for the same statement, "If the price of Apple is less than 150 then buy the apples".

if (price < 150)
{
	System.Console.WriteLine("Buy the apples");
}

Quite Simple! Right?

It works in two steps :

He goes to the market and asks the shopkeeper, "What is the price of Apples?".

Say the shopkeeper says, "The price is 120".

He notes the same in a price variable.
```
int price = 120;
```

Then he checks the if statement.
```
if (price < 150)
{
	System.Console.WriteLine("Buy the apples");
}
```
And finds that he can buy the apples as price is 120 which is less than 150.

Now, that we have seen the if statement. Let us look at the syntax of if statement in detail.

if (price < 150)
{
	System.Console.WriteLine("Buy the apples");
}

The above if statement begins with a if, followed by the actual condition (i.e. price < 150) then the if block starts with a brace { and ends with a brace }.

if (price < 150) {
	...
}

Now, if the above condition (i.e. price < 150) is true. The System.Console.WriteLine(...) statement is executed.

System.Console.WriteLine("Buy the apples");

There can be lot of statements inside the if statements. What I meant is, there can be a lot of System.Console.WriteLine statements.

if (price < 150)
{
	System.Console.WriteLine("Buy the apples");
	System.Console.WriteLine("The apples should be of good quality");
	System.Console.WriteLine("Take the apples in a carry bag");
}

So, in the above example we have seen your friend is happy because the price of apple is less than 150.

But what if the price of apple is more than 150. Say, the price of apple is 180. And he doesn't know what to do.

Example :

public class MyApplication
{
    public static void Main(string[] args)
     {
        int price = 180;
	    if (price < 150) 
	    {
		    System.Console.WriteLine("Buy the apples");
	    }
    }
}

Output :

And there is no output. Because the price of apple is 180 which is more than 150.

So, your friend comes back to you and you tell him to use else statement with if.

The 'else' statement for Decision Making

So, you tell your friend,

"If the price of Apple is less than 150 then buy the apples else do not buy the apples"

So, he writes the same thing in C# using else statement.

Example :

public class MyApplication
{
    public static void Main(string[] args)
     {
        int price = 180;
	    if (price < 150) 
	    {
		    System.Console.WriteLine("Buy the apples");
	    }
	    else
	    {
	        System.Console.WriteLine("Do not buy apples");
	    }
    }
}

Output :

Do not buy apples

So, to implement the line,

"If the price of Apple is less than 150 then buy the apples else do not buy the apples".

We have used the else statement along with if.

if (price < 150)
{
	System.Console.WriteLine("Buy the apples");
}
else
{
	System.Console.WriteLine("Do not buy apples");
}

The syntax of else statement is almost same as if. Else statement uses the else keyword right after the ending brace, } of if, followed by a starting brace {

}
else
{

And the statements inside else statement, should also be inside the starting brace { and the ending brace }.

else
{
	System.Console.WriteLine("Do not buy apples");
}

Now, your friend is happy. But you figured out that the shopkeeper is selling two types of apples for a fixed price.

1st kind of apple is 100 Bucks 2nd kind of apple is 200 Bucks.

And you give the new instruction to your friend.

The 'else if' statement for Decision Making

So, this time you tell your friend,

"If the price of Apple is 100 then is first kind of apple. Buy them else check if the price of apple is 200. Then it's second kind of apple. Buy them. It neither one is present then don't buy any apple".

And he writes the same in C#.

Example :

public class MyApplication
{
    public static void Main(string[] args)
     {
        int price = 200;
	    if (price == 100) {
		    System.Console.WriteLine("Buy 1st kind of apple");
	    } 
	    else if (price == 200) 
	    {
	    	System.Console.WriteLine("Buy 2nd kind of apple");
	    } 
	    else 
	    {
		    System.Console.WriteLine("Do not buy apples");
	    }
    }
}

Output :

Buy 2nd kind of apple

So, in the else part, if we need to provide a condition (i.e. price == 200).

We need to use else if.

else if (price == 200)
{
	System.Console.WriteLine("Buy 2nd kind of apple")
}

And the syntax of else if is just like if and else statement.

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C# - IF...ELSE

The if statement for Decision Making

Example :

Output :

He goes to the market and asks the shopkeeper, "What is the price of Apples?".

Then he checks the if statement.

Example :

Output :

The 'else' statement for Decision Making

Example :

Output :

The 'else if' statement for Decision Making

Example :

Output :