Displaying Fibonacci sequence

Question

wrote a program to calculate and display the first 20 fibonacci numbers, the sequence goes as follows:

1, 1, 2, 3, 5, 8, 13... (each number is the sum of the previous two numbers)

The problem is that the numbers that get displayed are from 2 onwards , the first and second numbers of the sequence do not get displayed , could someone tell me what needs to be done to correct this?

Code:

        private void button1_Click(object sender, EventArgs e)
    {
        int previousNumber = 1;
        int currentNumber = 1;
        int nextNumber = 1;

        while (currentNumber <= 11000)
        {
            nextNumber = previousNumber + currentNumber;
            previousNumber = currentNumber;
            currentNumber = nextNumber;
            textBox1.AppendText(Convert.ToString(nextNumber) + " ");
                nextNumber++;

        }
    }

Answer 1

I suggest carefully tracing through the logic and predicting what the computer will do at each step. Since the bug affects the very first output, you won't have to look at very many statements to encounter the problem. This is a basic skill for a programmer, so it will be well worth the time, especially since this sounds like homework.

Answer 2

Initially you need to display the current number twice before next number calculation. Also you need to move the number display before the next number calculation. Also next number should be previous number + currentNumber. I have made the changes to your code below which should work.

private void button1_Click(object sender, EventArgs e)
{
    int previousNumber = 1;
    int currentNumber = 1;
    int nextNumber = 1;

    textBox1.AppendText(Convert.ToString(currentNumber) + " ");
    while (currentNumber <= 11000)
    {
        textBox1.AppendText(Convert.ToString(currentNumber) + " ");
        nextNumber = previousNumber + currentNumber;
        previousNumber = currentNumber;
        currentNumber = nextNumber;

            nextNumber = previousnNumber + currentNumber;

    }
}

Answer 3

Since the first two digits in a Fibonacci are the seed values (1 and 1 or 0 and 1) you should print those first and then calculate the next values.

I would simplify the code. You can test it out at https://dotnetfiddle.net/3cV96L

int initialSeed = 1;
int currentNumber = 1;

//Write seed values
Console.Write("{0} {1} ", initialSeed, currentNumber);

while (currentNumber <= 11000)
{
    currentNumber += currentNumber;
    Console.Write(currentNumber + " ");
}

Answer 4

Just change int currentNumber = 0;