FPDF skips first row - php

Question

I wrote a simple FPDF code but I ran into a problem.
For some reason, the for loop skips the first row ( cell 1, cell 2, cell 3 ).
Code:
<?php
require('temp/fpdf.php');
class PDF extends FPDF
{
function Header(){
$this->SetY(0);
$this->SetFont('Arial','I',8);
$this->Cell(0,5,'Page '.$this->PageNo(),0,0,'C');
}
function Footer(){
$this->SetY(-5);
$this->SetFont('Arial','I',8);
$this->Cell(0,5,'Page '.$this->PageNo(),0,0,'C');
}
}
$pdf = new PDF();
$pdf->SetMargins(0,0,0);
$pdf->AddPage();
$pdf->SetFont('Times','',12);
for($i=0;$i<=24;$i++){
$pdf->Cell(70,30,'Printing line number '.$i,0,0,'C');
if(($i%3==0)&&($i!=0)){
$pdf->Ln();
}
}
$pdf->Output();
?>
I'm staring at the code for hours but I can't find the answer so any help is appreciated.

Answer 1

Your first set of printing is floating over to the right side. As a quick-fix try adding to add a line break and clear up unwanted floats in the PDF definition.
Add
$pdf->Ln();
after
$pdf->AddPage();

Answer 2

I see two possibilities that you might want to check. The first is that the margins are all zero, but in order for a PDF to print or save correctly, they need to be 1" on top/bottom and .5" on the sides. Also you have to consider that the first iteration of your loop $i will equal 0, and your first cell will print out 0 and not 1. Let me know if that doesn't pan out, and I can help more. I'm actually in the middle of a huge FPDF project and have found many nuances.
I just noticed this:
if(($i%3==0)&&($i!=0)){
$pdf->Ln();
}
Use this http://calculator.sdsu.edu/calculator.php to calculate the Modulus using your $i values and you'll see 0%3=0, 1%3=4, 2%3=5. That will skip your first line.
I personally would've written it like this:
$i = 1;
while($i <=25)
{
$pdf->Cell(70,30,'Printing line number '.$i,0,0,'C');
if(($i % 3) == 0)
{
$pdf->Ln();
}
}