PHP - concatenate or directly insert variables in string

Question

I am wondering, What is the proper way for inserting PHP variables into a string?

This way:

echo \"Welcome \".$name.\"!\"


        

Answer 1

Either one is fine. Use the one that has better visibility for you. And speaking of visibility you can also check out printf.

Answer 2

It only matter of taste.
Use whatever you wish.

Most of time I am using second one but it depends.

Let me suggest you also to get yourself a good editor which will highlight a variable inside of a string

Answer 3

I know this is an old question, but I think someone has to mention all pros & cons:

Better Syntax: That's personal preference.

Performance: No difference. As many mentioned, double-quote might be faster if using unrealistically many variables.

Better Usage: Single quote (mostly). As @Khez said, with single quote you can concatenate anything, even function calls and variable modification, like so: echo 'hi ' . trim($name) . ($i + 1);. The only thing double-quote can do that single-quote cannot do is usage of \n, \r, \t and alike.

Readability: No difference (may personal preference apply).

Writability/Re-Writability/Debugging: In 1-line statements there is no difference, but when dealing with multiple lines, it's easier to comment/uncomment lines while debugging or writing. For example:

$q = 'SELECT ' .
     't1.col1 ' .
     ',t2.col2 ' .
   //',t3.col3 ' .
     'FROM tbl1 AS t1 ' .
     'LEFT JOIN tbl2 AS t2 ON t2.col2 = t1.col1 ' .
   //'LEFT JOIN tbl3 AS t3 ON t3.col3 = t2.col2 ' .
     'WHERE t1.col1 = ' . $x . ' ' .
     '  AND t2.col2 = ' . $y . ' ' .
   //'  AND t3.col3 = ' . $z . ' ' .
     'ORDER BY t1.col1 ASC ' .
     'LIMIT 10';

Less Escaping: Single-quote. For single quote you need to escape 2 characters only (' and \). For double quote you need to escape 2 characters (", \) and 3 more if required ($, { and }).

Less Changes: Single quote. For example if you have the following code:

echo 'Number ' . $i . '!';

And you need to increment 1 to $i, so it becomes likes:

echo 'Number ' . ($i + 1) . '!';

But for double quote, you will need to change this:

echo "Number $i!";

to this:

echo "Number " . ($i + 1) . "!";

---

Conclusion: Use what you prefer.

Answer 4

Double-quoted strings are more elegant because you don't have to break up your string every time you need to insert a variable (like you must do with single-quoted strings).

However, if you need to insert the return value of a function, this cannot be inserted into a double-quoted string--even if you surround it with braces!

//syntax error!!
//$s = "Hello {trim($world)}!"

//the only option
$s = "Hello " . trim($world) . "!";

Answer 5

I use a dot(.) to concate string and variable. like this-

echo "Hello ".$var;

Sometimes, I use curly braces to concate string and variable that looks like this-

echo "Hello {$var}";

Answer 6

Since php4 you can use a string formater:

$num = 5;
$word = 'banana';
$format = 'can you say %d times the word %s';
echo sprintf($format, $num, $word);

Source: sprintf()