PHP Output of NULL/Spaces

Question

I'm trying to output from mysql using php. The SQL query that I'm outputting contains several joins and some of the values are NULL. When I echo the output I get empty spaces for the NULL values. How do I get rid of the empty space? I have line breaks between each value that I want to output, but the NULL values are just placing an empty space. So my output looks a bit like this.

What it looks like

Dave Smith
Subject 1

Subject 3

John Smith
Subject 1
Subject 2

Subject 4

What I'd like it to look like

Dave Smith
Subject 1
Subject 3

John Smith
Subject 1
Subject 2
Subject 4

I have tried a few of the php trim functions, but none seem to work. The relevant code is below.

$resultSet = $db->query ("...my query");  

echo $resultSet -> num_rows;

While($rows = $resultSet ->fetch_assoc())

{
  $FirstName = ($rows['First_Name']);
  $Surname =   ($rows['Surname']);
  $subject1 = ($rows['subject1']);
  $subject2 = ($rows['subject2']);
  $subject3 = ($rows['subject3']);
  $subject4 = ($rows['subject4']);

  $output .= "<p> $FirstName $Surname <br/> Chosen Subjects <br/> $subject1 <br/> $subject2 <br/> 
  $subject3 <br/>  $subject4 </p>";
 }

Answer 1

When I echo the output I get empty spaces for the NULL values

$subject1 = ($rows['subject1']);
$subject2 = ($rows['subject2']);
$subject3 = ($rows['subject3']);
$subject4 = ($rows['subject4']);

  $output .= "<p> $FirstName $Surname <br/> Chosen Subjects <br/> $subject1 <br/> 
  $subject2 <br/>  $subject3 <br/>  $subject4 </p>";

The reason for your empty space is that you are putting in <br/> regardless as to if any PHP value is present.

Suggested Alternative:

• Put the values into an array.
• Clean any falsey / null values from the array
• implode the array into the final string.

a) Put the values into an array:

$subject[1] = $rows['subject1'];
$subject[2] = $rows['subject2'];
$subject[3] = $rows['subject3'];
$subject[4] = $rows['subject4'];

b) Clean out the null values reference

$subjectOutput = array_filter($subject, 'strlen');

Note: If you don't care about other falsey values such as 0 then you can simply do an even more basic array_filter() call such as = array_filter($subject);.

c) Implode the array.

$subjectString = implode($subjectOutput, '<br/>');

Example:

$subject[1] = "horses";
$subject[2] = 12;
$subject[3] = 0;
$subject[4] = null;
$subject[5] = "cats";

$subjectOutput = array_filter($subject, 'strlen');

//$subject[1] = "horses";
//$subject[2] = 12;
//$subject[3] = 0;
//$subject[5] = "cats";

/***
 * simply print the sting and voila!
 ***/
$subjectString = implode($subjectOutput, '<br/>');

// $subjectString = "horses<br/>12<br/>0<br/>cats";

 $output .= "<p> $FirstName $Surname <br/> Chosen Subjects <br/> ".$subjectString." </p>";