Jump to content

PHP codeacademy problem ( do/while )


Recommended Posts


I am learning PHP and made a codeacademy PHP online course. Basic stuff and interesting course for free.

But there is a do/while exercise I can't get my head around:



In the following, there is a flipcoin example, which flips, as long the result is head.

In the do statement there is the if and the else 

The if condition is $flip and it echoes a H letter for Head. The else echoes a T for Tail.

$flip is random 0 or 1

My question:

How can the if and else statements be H or T if $flip is random? I don't understand the $flip variable, because in my head it can be 0 or 1.....therefor if is not one fixed value, because of the rand(0,1) it can change

How does the programm to put out a H or a T?

I hope my question is clear enough



Thanks for any clarification


<!DOCTYPE html>
    	<link type='text/css' rel='stylesheet' href='style.css'/>
		<title>More Coin Flips</title>
	<p>We will keep flipping a coin as long as the result is heads!</p>
	$flipCount = 0;
	do {
		$flip = rand(0,1);
		$flipCount ++;
		if ($flip){
			echo "<div class=\"coin\">H</div>";
		else {
			echo "<div class=\"coin\">T</div>";
	} while ($flip);
	$verb = "were";
	$last = "flips";
	if ($flipCount == 1) {
		$verb = "was";
		$last = "flip";
	echo "<p>There {$verb} {$flipCount} {$last}!</p>";


Link to comment
Share on other sites

if($flip) {
  echo "H"

You are exactly right, I think you just miss a thought:

The condition relates to the value of $flip. The value is either 0 or 1. And in PHP, 1 in a condition is “like” true, and 0 is “like” false.

So $flip may be 1. In that case PHP will coerce it to true and finally print H because the condition is met.
If $flip is 0, PHP will coerce that to false and print T because the condition for the if() was not met. So the else block is executed.

Hope that helps?

  • Like 7
Link to comment
Share on other sites

Just wanted to add that it's not just PHP that treats 0 as False and 1 as True. 
You'll find most (traditional) languages will do the same (at least the ones I've come across).

There are some exceptions like Ruby & Lisp which treats 0 as true,  AFAIK.

If you're wondering why 0s & 1s ... well I don't have a definite answer myself as it's one of those topics that will divide opinion.
IMHO I side with the view that it originates from Electronics & Boolean Algebra.
But it certainly sounds like a question for Quora :)

  • Like 3
Link to comment
Share on other sites


  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Similar Content

    • By Joachim
      Long time user and huge fan of PW, but this time I can't find an answer to my question this time:
      For my social media buttons, I have a Repeater field called var_link_web with two fields: one is for the URL, and the other is an Images field containing two images that are used as a background-image for a <div>, of which the second is the ':hover' version (although activated through JavaScript here). 
      There are four instances of this Repeater, of which two are 'turned off'.
      I use the following PHP in my _main.php to call them, wrapped in <p><?php == ?></p>:
      $s_m_button = $variables->var_link_web; foreach($s_m_button as $button){ $button_image = $button->var_link_image->first->height(80); $button_image2 = $button->var_link_image->eq(1)->height(80); echo " <a href='$button->var_link_url'> <div class='image_link' style='background-image:url({$button_image->url})' onMouseOver='this.style.backgroundImage=url({$button_image2->url})' onMouseOut='this.style.backgroundImage=url({$button_image->url})'> </div> </a>"; }; ($variables leads to an unpublished page with several fields I want to have easy access to, and is defined in _init.php.)
      However, this gives me the following result:

      I have no idea where the extra <p>'s come from. The URL field has the 'HTML Entity Encoder' turned on. What's even weirder is that the HTML source file seemingly renders correctly:
      <p> <a href='https://www.facebook.com/'> <div class='image_link' style='background-image:url(/site/assets/files/1045/icons-facebook-square.0x80.png)' onMouseOver='this.style.backgroundImage="url(/site/assets/files/1045/icons-facebook-square2.0x80.png)"' onMouseOut='this.style.backgroundImage="url(/site/assets/files/1045/icons-facebook-square.0x80.png)"'> </div> </a> <a href='https://www.instagram.com/'> <div class='image_link' style='background-image:url(/site/assets/files/1046/icons-instagram-square.0x80.png)' onMouseOver='this.style.backgroundImage="url(/site/assets/files/1046/icons-instagram-square2.0x80.png)"' onMouseOut='this.style.backgroundImage="url(/site/assets/files/1046/icons-instagram-square.0x80.png)"'> </div> </a> </p> Removing the JavaScript has no effect. I'm probably missing something obvious, but am at a loss here.
      Thank you in advance!
    • By Marvin
      Hello, excuse me
      I'm new at processwire, i want to ask about a master detail system (Inheritance system) using a processwire. Can we create a Inheritance table using a processwire, and how we create it? Thank you for the help
    • By Marvin
      I'm still new at processwire, i want to ask, i was create a website with sign in system, but i want to add a access roles/permission for each user at my website. For now, i just can create a login user without any permission and the user data became as a pages in my processwire.
      Here i attach my code for login
      <?php $note = $note2 = $hidden =""; if($input->get->id == "logout") { $session->remove('login_id'); } if($input->post->submit) { $email = $sanitizer->email($input->post->email); $pass = $sanitizer->text($input->post->pass); $result = $pages->find("email=$email, text_1=$pass"); if(!$email || !$pass) { $note = "Data belum lengkap"; } else { if($result->count > 0) { $session->login_id = "$result"; $hidden = "style = 'diplay:none'"; $url=$pages->get("/files/")->httpUrl; header("Location:$url"); die(); } else { $note = "Akun tidak ditemukan"; } } } ?> And this code for login form
      <div class="frow-container"> <div class="frow centered mt-50"> <div class="col-md-1-3"> <div class="box p-40 shadow-light"> <h2 class="mb-20 text-center" <?=$hidden?>>Database Partitur<br>GII HIT</h2> <form method="post" <?=$hidden?>> <label>Username <input type="text" name="email"></label> <label>Password <input type="password" name="pass"></label> <input type="submit" name="submit" value="Masuk"> </form> <p class="notif"><?=$note;?></p> <div class="text-center"><?=$note2;?></div> </div> </div> </div> </div> Just for remember, my user data now is a pages, and i cannot give any permission to user data.
      Thank you very much for help.
    • By Marvin
      I'm new at process wire and i want to make an web using upload file and showing it at the table as a link to open it at the new tab. I wa succed while upload a file, but how i showing it as a link at the table to open it at the new tab of my browser? Any suggestion may helpfull
      Here i attach my code below :
      This code is for upload it to back-end (process wire)
      <?php $note = $note2 = $hidden =""; if($input->post->submit){ $upload_path = $config->paths->assets.'files/upload/'; if(!is_dir($upload_path)){ if(!wireMkdir($upload_path)) throw new WireException("No upload path"); } $original = $sanitizer->text($input->post->original); $indonesia = $sanitizer->text($input->post->indonesia); $other = $sanitizer->text($input->post->other); $composer = $sanitizer->text($input->post->composer); if(!$original || !$indonesia || !$other || !$composer){ $note = "Data tidak lengkap"; } else { $newFile = new WireUpload("song_files"); $newFile->setMaxFiles(1); $newFile->setOverwrite(false); $newFile->setDestinationPath($upload_path); $newFile->setValidExtensions(array('pdf','docx','doc')); $files = $newFile->execute(); if(!count($files)) { $newFile->error("No files received, so not creating page."); return false; } $newImg = new WireUpload("img_files"); $newImg->setMaxFiles(1); $newImg->setOverwrite(false); $newImg->setDestinationPath($upload_path); $newImg->setValidExtensions(array('jpeg','jpg','png','gif')); $files = $newImg->execute(); if(!count($files)) { $newImg->error("No files received, so not creating page."); return false; } $newPage = new Page(); $newPage->template = "files"; $newPage->parent = $pages->get("/files/"); $newPage->title = $original; $newPage->text_1 = $indonesia; $newPage->text_2 = $other; $newPage->text_3 = $composer; $newPage->of(false); $newPage->save(); foreach($files as $filename) { $filepath = $upload_path . $filename; $newPage->files->add($filepath); $newPage->message("Add file : $filename"); unlink($filepath); } $newPage->save(); } } ?> and this code to showing it as a link at the table
      <table class="border"> <tr> <th>No.</th> <th>Original Song Title</th> <th>Indonesia Song Title</th> <th>Other Song Title</th> <th>Composer</th> <th>File (pdf)</th> </tr> <?php $num = 1; $song; foreach($pages->get("/files/")->children as $child) { //showing every child at files parent directory $page == $child; $song = $pages->get("/files/".$child->id."/")->files; //showing uploaded files at child directory echo $child->id; echo "<tr><td>".$num++.".</td><td>".$child->title."</td><td>".$child->text_1."</td><td>".$child->text_2."</td><td>".$child->text_3."</td><td><a href='".$song->httpUrl."'</a>".$song->name."</td></tr>"; } ?> </table> Thank you for any suggestion
    • By picarica
      so i am trying to fetch dimensions of image using getimagesize() but it returns nothing, at least i think so, i want to feed it to data attribute, bit its emtpy, i tried feeding it the image directly or just image->url
      here is my source code

      foreach($page->repeat_body as $r_body) { /* other code here*/ if ($r_body->gallery_check == 1) { echo "<div class='my-gallery' id='grid-gallery' itemscope itemtype='http://schema.org/ImageGallery'>"; foreach($r_body->image as $image) { $options = array('quality' => 80, 'upscaling' => true, 'cropping' => 'north', 'sharpening'=>'medium'); $thumb = $image->size(400, 400, $options); $large = $image->size(1280, 0, $options); list($width, $height) = getimagesize($image->url); echo " <figure itemprop='associatedMedia' itemscope itemtype='http://schema.org/ImageObject'> <a href='$large->url' itemprop='contentUrl' data-size='$widthx$height' data-index='0'> <img src='$thumb->url' height='$height' width='$width' itemprop='thumbnail' alt='Beach'> </a> </figure>"; } echo "</div>"; } /* other code here*/ } now, the images are outputted correctly, i can open then and browse them
  • Create New...