What does the code img src="'.$target.'" mean?

Question

 <?php
    define('upload', 'images/');

    if (isset($_POST['submit'])) {

         $name=$_POST['name'];
         $score=$_POST['score'];
         $screenshoot=$_FILES['screenshoot']['name'];
         $target=upload.$screenshoot;
         move_uploaded_file($_FILES['screenshoot']['tmp_name'], $target);           
         if(!empty($name)&&!empty($score)){
          $dbc=mysqli_connect('localhost','root','57317019','guitar_game');
          $query="INSERT INTO guitargame(id,date,name,score,screenshoot".
          "values(0,NOW(),'$name','$score','$screenshoot')";
          $result= mysqli_query($dbc,$query);

          mysqli_close($dbc);
            }
         else{
            echo "Please fill out all the blanks";
             }

          }

         echo "<p>Thanks for adding your new high score!</p>";
         echo "<p><strong>Name:</strong>"."$name</p>";
         echo "<p><strong>Score:</strong>"."$score</p>";
         echo '<img src="'.$target.'">';
         echo '<p><a href="index.php">Back to high scores</a></p>';
       ?>

l wanna asked what does the img src="'.$target.'" means? Why not use img src="$target" instead? Thanks in advance! I am new to php.

Because the outer string is using single quotes and $vars are not expanded in single quotes — RiggsFolly, Jan 22 '17 at 15:31
@Fred-ii- Not sure just marking this as a "duplicate" will really help Mr.tang learn... — wogsland, Jan 22 '17 at 15:44
@Fred-ii- I think it might be hard for a new comer to know how to google that - he is effectively asking when to use string interpolation vs concatenation. Also, the 'duplicate' question does not answer the question of when to use one over the other. — Bryan, Jan 22 '17 at 15:46
@wogsland This answer in the duplicate I closed it with http://stackoverflow.com/a/3446229/1415724 contains that explanation. — Funk Forty Niner, Jan 22 '17 at 15:46
@ All: This OP has a bad track record and does not do the necessary research before asking, nor do they mark any questions as solved; such as this one won't. — Funk Forty Niner, Jan 22 '17 at 15:47

score -1 · Accepted Answer · answered Jan 22 '17 at 15:33

The difference between

echo '<img src="'.$target.'">';

and

echo "<img src=\"$target\">";

is that in the former strings are concatenated whereas in the latter the double quotes need to be escaped inside the string to use double quotes which are required to process the variable inside the string. Using just img src="$target" would not work in the echo in either case.

score -1 · Answer 2 · answered Jan 22 '17 at 15:33

Short answer:

echo '<img src="'.$target.'">';

gives an equal result to

echo "<img src=\"$target\">";

Longer answer: the PHP parser looks inside the "..."-style tags for any variables to replace. It doesn't look inside the '...'-style tags. So the latter is a bit faster. You will only notice a difference when this is inside a loop that is executed hundreds of times.

What does the code img src="'.$target.'" mean?

2 Answers2