C# program to demonstrate an example of nested if-else statement

Syntax:

    if(test_condition1){
     //code section 1
     if(test_condition_a){
     //code section a
    }
    else{
     //code section b
    }
    }
    else if(test_condition2){
    {
     //code section 2
    }
    else if(test_condition3){
     //code section 3
    }
    ...
    else{
     //else code section
    }

C# example for nested if-else statement:

// C# program to demonstrate example of 
// nested if else statement 
using System;
using System.IO;
using System.Text;

namespace JustTechReview
{
    class Test
    {
        // Main Method 
        static void Main(string[] args)
        {
            //input a character and check whether it is vowel or consonant 
            //but before it - check input character is an aplhabet or not
            char ch;
            Console.Write("Enter a character: ");
            ch = Console.ReadLine()[0];

            //check ch is an alphabet or not
            if((ch>='A' && ch<='Z') || (ch>='a' && ch<='z')){
                Console.WriteLine("{0} is a valid alphabet", ch);
                //checking for vowel or consonant
                if (ch == 'A' || ch == 'a' || ch == 'E' || ch == 'e' ||
                    ch == 'I' || ch == 'i' || ch == 'O' || ch == 'o' ||
                    ch == 'U' || ch == 'u')
                {
                    Console.WriteLine("{0} is a vowel", ch);
                }
                else
                {
                    Console.WriteLine("{0} is a consonant", ch);
                }
            }
            else{
                Console.WriteLine("{0} is not a valid alphabet",ch);
            }
			
            //hit ENTER to exit the program
            Console.ReadLine();
        }
    }
}

Output:

First run:
Enter a character: X
X is a valid alphabet
X is a consonant

Second run:
Enter a character: u
u is a valid alphabet
u is a vowel

Third run:
Enter a character: $
$ is not a valid alphabet