Online Test Banks
Score higher
See Online Test Banks
eLearning
Learning anything is easy
Browse Online Courses
Mobile Apps
Learning on the go
Explore Mobile Apps
Dummies Store
Shop for books and more
Start Shopping

How to Display PHP Variable Values

You can display the value in a PHP variable on a web page by using any of the following statements: echo, print, print_r, or var_dump.

Variables in echo and print statements

You can display the value in a variable on a web page with an echo or print statement. For instance, if you set the $age variable to 12 and then use the following PHP echo statement in a PHP section, the output is 12.

echo $age;

If you include the following line in an HTML file:

<p>Your age is <?php echo $age ?>.</p>

the output on the web page is

Your age is 12.

For the purposes of the table, assume that $string1 is set to Hello and $string2 is set to World!.

print Statements
print Statement Output
print $string1; Hello
print $string1,$string2; HelloWorld!
print "$string1 $string2"; Hello World!
print "Hello ",$string2; Hello World!
print "Hello"," ",$string2; Hello World!
print '$string1',"$string2"; $string1World!

Single and double quotes have different effects on variables, as follows.

  • Single quotes (' '): When you use single quotes, variable names are echoed as is.

  • Double quotes (" "): When you use double quotes, variable names are replaced by the variable values.

Sometimes you need to enclose variable names in curly braces ({ }) to define the variable name. For instance, the following statements won’t output bird as the $pet variable.

$pet = "bird";
echo "The $petcage has arrived.";

In other words, the output won’t be The birdcage has arrived. Rather, PHP will look for the variable $petcage and won’t be able to find it. You can echo the correct output by using curly braces to separate the $pet variable:

$pet = "bird";
echo "The {$pet}cage has arrived.";

The preceding statement gives you

The birdcage has arrived.

How long a variable holds its value

A variable keeps its information for the entire script, not just for a single PHP section. If a variable is set to “yes” at the beginning of a file, it will still hold “yes” at the end of the page. For instance, suppose your file has the following statements:

<p>Hello World!</p>
<?php
    $age = 15;
    $name = "Harry";
?>
<p>Hello World again!</p>
<?php
    echo $name;
?>

The echo statement in the second PHP section will display Harry. The web page resulting from these statements is

Hello World!
 
Hello World again!
 
Harry

Display variables with print_r statements

PHP provides a function named print_r for looking at the value in a variable. You can write the following statements to display a variable value:

$weekday = "Monday";
print_r($weekday);

The output from print_r is

Monday

Display variables with var_dump statements

PHP provides a function named var_dump that you can use to display a variable value and its data type.

You can write the following statements to display a variable value:

$weekday = "Monday";
var_dump($weekday);

The output of var_dump is

string(6) "Monday"

The output shows that the value in $weekday is Monday. The output also shows that the value is a string data type that is six characters long.

You'll use var_dump frequently for troubleshooting PHP. Its use is essential for that purpose.

  • Add a Comment
  • Print
  • Share
blog comments powered by Disqus
Advertisement

Inside Dummies.com

Dummies.com Sweepstakes

Win $500. Easy.