FizzBuzz: Code-Along

FizzBuzz is a classic technical interview question. The problem is stated as follows:

Write a short program that prints each number from 1 to 100 on a new line.

• For each multiple of 3, print "Fizz" instead of the number.
• For each multiple of 5, print "Buzz" instead of the number.
• For numbers which are multiples of both 3 and 5, print "FizzBuzz" instead of the number.

Part 1 - for loop set up

1. Build out the for loop structure:
   • for keyword
   • Parentheses (())
   • Within the parentheses: two semi-colons (;)
   • After the parentheses: curly brackets ({})
2. Fill in the for loop init, conditional, and increment:
   • int i = 1
   • i <= 100
   • i++

for (int i = 1; i <= 100; i++)
{

}

Part 2 - Body of the for loop

1. Print the current number i
   • Verify that each number, 1 to 100, is printed
2. If i is a multiple of 3, print "Fizz"
   • Use modulo (%) to determine if i is divisible by 3
   • Use an if and an else so that it does not print the number if divisible by 3
3. If i is a multiple of 5, print "Buzz"
   • Use an else if to accomplish this
4. If i is a multiple of 3 AND 5, print "FizzBuzz"
   • This has to be the first check

for (int i = 1; i <= 100; i++)
{
    if (i % 3 == 0 && i % 5 == 0)
    {
        Console.WriteLine("FizzBuzz");
    }
    else if (i % 3 == 0)
    {
        Console.WriteLine("Fizz");
    }
    else if (i % 5 == 0)
    {
        Console.WriteLine("Buzz");
    }
    else
    {
        Console.WriteLine(i);
    }
}

Part 3 - User input

1. Before the for loop, use Console.ReadLine to receive a number from the user
2. Convert the string into a number
3. Use the number as the top limit in the for loop

Console.WriteLine("Enter a Number");
int topNum = Convert.ToInt32(Console.ReadLine());

for (int i = 1; i <= topNum; i++)
{
    if (i % 3 == 0 && i % 5 == 0)
    {
        Console.WriteLine("FizzBuzz");
    }
    else if (i % 3 == 0)
    {
        Console.WriteLine("Fizz");
    }
    else if (i % 5 == 0)
    {
        Console.WriteLine("Buzz");
    }
    else
    {
        Console.WriteLine(i);
    }
}