Learn PHP-19 : Concatenation Assignment Operators

The concatenation operator ( . ) returns the combined value of its right and left values. The variable’s data type has an affect on the output.

Here are code examples using the concatenation operator ( . ) to unite or combine variable values

<?php
echo "deve"."lop";          //displays "develop"
echo "<br /><br />";            // html line breaks

echo "deve" . "lop";        //displays "develop"
echo "<br /><br />";            // html line breaks

echo 4 . 3;                     //displays "43"
echo "<br /><br />";            // html line breaks

echo 4.3;                       //displays "4.3"
echo "<br /><br />";            // html line breaks

echo "4" . "3";                //displays "43"
echo "<br /><br />";            // html line breaks

echo '4' . '3';                  //displays "43"
?>

The concatenating assignment operator ( .= ), which appends the variable value on the right side to the variable on the left side. We use this method many times to compound and keep adding to one variable so it will retain its current value, and just append the new values onto the current value’s tail end.

Here is a code example using the concatenating assignment operator ( .= ) to append or compound values

<?php
$var1 = "Hello World!";
$var2 = "We are silly!";
$htmlOutput = ''; // set as empty, but defined

// notice the period before each ( = ) sign... that is concatenating them onto the original var value
$htmlOutput .= '<table bgcolor="#663366" cellpadding="8">';
$htmlOutput .= '<tr>';
$htmlOutput .= '<td bgcolor="#CCCCCC">';
$htmlOutput .= ' ' . $var1 . ' ';
$htmlOutput .= '</td>';
$htmlOutput .= '<td bgcolor="#FFFF00">';
$htmlOutput .= ' ' . $var2 . ' ';
$htmlOutput .= '</td>';
$htmlOutput .= '</tr>';
$htmlOutput .= "</table>";
// Now print or echo the output
echo "$htmlOutput ";
?>

The output is shown below :

Hello World!

We are silly!