What are the advantages of using PHP’s sprintf function?

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I can see an advantage in using the function sprintf in place of concatenation: readability. In addition to readability, what are the other advantages of sprintf() in relation to concatenation? Is there any advantage when translating applications?

php string function encoding-style string-concatenation
  • 4

    Readability depending on the case right? I can’t imagine that one sprintf is more legible than a echo "Nome: $nome";

3 answers

3

The advantage is more this same, readability and ease in more complex cases. Not simple concatenations need conversions, formatting, and manual making takes more work. And here comes another advantage derived from this, it’s very easy to make mistakes by doing it manually, so it’s a more robust way too. Probably more efficient because it is something processed in C code and not PHP that is much slower.

If you do right it does not matter from the point of view of application translation.

2


I do not agree that it is a question of comparing which is better or necessarily which advantages of one under the other, sprintf() may seem "easier" or advantageous, but what defines this is the need, then the advantage is when "it is necessary", I am not saying that will have disadvantages in using deliberately, really will not have "big losses".

The point is that both sprintf how much printf do much more of joining and popular a string, they have different features that can be useful in different situations, for example adding zeros in front of dates:

<?php

$dia = 1;
$mes = 5;
$ano = 2019;

$hora = 2;
$minutos = 3;

printf('%02d/%02d/%04d - %02d:%02d', $dia, $mes, $ano, $hora, $minutos);

This makes it easy, because without the printf/sprintf you would need to use str_pad or even ifs to check, example:

$dia = 1;
$mes = 5;
$ano = 2019;

$hora = 2;
$minutos = 3;

$dia = str_pad($dia, 2, 0, STR_PAD_LEFT);
$mes = str_pad($mes, 2, 0, STR_PAD_LEFT);
$ano = str_pad($ano, 4, 0, STR_PAD_LEFT);
$hora = str_pad($hora, 2, 0, STR_PAD_LEFT);
$minutos = str_pad($minutos, 2, 0, STR_PAD_LEFT);

echo "$dia/$mes/$ano - $hora:$minutos";

in this case it is quite evident how much you can facilitate writing and even understanding the code using printf/sprintf, now in a simple scenario, just "popular" the values in a string, without needing to adjust such values you can simply make use of double quotes.

There is talk that single quotes (apostrophes) are more efficient than double quotes, but the performance advantage is so insignificant or often nonexistent that doing so:

echo 'Horário de hoje', $hora, ':', $minutos, ' - data: ', $dia, '/', $mes, '/', $ano;

You have no advantage in doing this:

echo "Horário de hoje $hora:$minutos - data: $dia/$mes/$ano";

Even in stress tests with a lot of data I could not notice big differences. Returning the question of the question, for example if you need to escape HTML tags to entities (avoiding "html injection" that could not occur) you will have to use htmlspecialchars and in this case will have to treat variable by variable, as far as I know the sprintf you won’t be able to solve it by staying something like:

$user = htmlspecialchars($data['usuario']); //Dado hipotético vindo do banco
$msg = htmlspecialchars($data['mensagem']); //Dado hipotético vindo do banco

echo "<p><strong>$user</strong>:<br>$msg</p>";

Idea of "templates"

A scenario that might be interesting would be if the strings were stored as well and the values were populated, for example on a site with different languages, then in files .ini or .php you could store something like:

./langs/
  +---- pt.ini
  +---- en.ini
  +---- es.ini

In the content of pt.ini would have something like:

main_title=Site %s
main_subtitle=O maior site do seguimento de %s
main_footer=Todos direitos reservados %04d

In the en.ini, something like:

main_title=%s website
main_subtitle=The biggest site in the segment of %s
main_footer=&copy; %04d. All rights reserved

<?php

...

$idioma = $data['usuario_idioma'];
$parsed = parse_ini_file($idioma . '.ini');

?><!DOCTYPE html>
<html>
<head>
    <title><?=printf($parsed['main_title'], 'Foo Bar')?></title>
</head>
<body>
    <h1><?=printf($parsed['main_title'], 'Foo Bar')?></h1>
    <h2><?=printf($parsed['main_subtitle'], 'tecnologia')?></h2>

    <footer>
        <?=printf($parsed['main_footer'], 'tecnologia')?>
    </footer>
</body>
</html>

But this is just one example.

Database and queries

I personally disagree with the chosen answer that says this:

insert many variables into a string, query

At least in PHP specifically and if query refer to database, really has no advantage, this because in Apis mysqli and PDO there are bindParam/bindValue, because you do not use Binds with or without sprintf you would have to escape variables to avoid sql-injectection or avoid syntax errors in the query, but with native Apis Binds it will be similar to sprintf, for example in mysqli:

$stmt = mysqli_prepare($link, "INSERT INTO Log VALUES (?, ?, ?, ?)");
mysqli_stmt_bind_param($stmt, 'ssdd', $user, $language, $score, $percent);

$user = 'Rcs';
$language = 'pt-BR';
$score = 10;
$percent = 11.2;

/* executa */
mysqli_stmt_execute($stmt);

0

In my view, when you need to insert many variables in a string, query, among others, it makes it much easier, because when concatenating we would have to open and close single and double quotes and then add the concatenation. In sprintf just add the terms (%s) for string and (%d) for integer (there are several others), for example, which the function will replace automatically. It’s much more practical.

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