The function sprintf() formats a string based on the order of the parameters defined in the first argument, which makes everything very dynamic, allowing you to format strings with a lot of flexibility.
An example of great utility is when you need to write data in different languages.
Formatting for templates, output of data, etc.
Common cases are names of people, personal pronouns, addresses, etc.
The example below elucidates better:
// Define idioma. Modifique para "pt" e veja como é a saída dos dados.
$l = 'ja';
// tratamento pessoal
$t['ja'] = '様';
// nome da pessoa
$n['ja'] = array('name' => '太郎', 'surname' => '山田');
// endereço
$a['ja'] = array(
'postal_code' => '104-0045',
'country_name' => '日本',
'province_name' => '東京都',
'city_name' => '東京',
'city_subregion' => '中央区',
'county_name' => '明石町',
'building' => 'マンション名123'
);
// tratamento pessoal
$t['pt'] = 'Sr(a)';
// nome da pessoa
$n['pt'] = array('name' => 'Fulano', 'surname' => 'Silva');
// endereço
$a['pt'] = array(
'postal_code' => '06453-040',
'country_name' => 'Brasil',
'province_name' => 'SP',
'city_name' => 'Barueri',
'city_subregion' => '',
'county_name' => 'Alphaville',
'building' => 'Calçadas das Papoulas 123'
);
// regra de formatação para idioma japonês
$nf['ja'] = '%3$s %2$s %1$s'; // nome
$af['ja'] = '〒%1$s %2$s %3$s %4$s %5$s %6$s %7$s'; // endereço
// regra de formatação para idioma português
$nf['pt'] = '%1$s %2$s %3$s'; // nome
$af['pt'] = '%7$s %6$s'.(empty($a[$l]['city_subregion'])? '': '- %5$s').', %4$s - %3$s, %1$s, %2$s'; // endereço
// escreve o nome
echo sprintf($nf[$l], $t[$l], $n[$l]['name'], $n[$l]['surname']).'<br>';
// escreve o endereço
echo sprintf(
$af[$l],
$a[$l]['postal_code'],
$a[$l]['country_name'],
$a[$l]['province_name'],
$a[$l]['city_name'],
$a[$l]['city_subregion'],
$a[$l]['county_name'],
$a[$l]['building']
);
Note that at the time of writing, nothing changes. The structure of the data in the arrays also does not change. Both are the same. What makes the difference is the formatting rule, which informs the sprintf() function how and where to concatenate the other parameters.
Try to try to get to the same result without using the function. It becomes complicated with many conditionals in a tangle of codes. A nightmare.
This is an example only for 2 languages and is a very simple and "easy" case. There are more complex things, however, the above example is enough for the one asking the question.
Number formatting
There are several other utilities for using the function, such as converting a number in scientific notation format to decimal / float.
$n = '5.3882598876953E-5';
// Esse trecho é para obter o exponente. Não é relevante para a questão
if ($p = strpos($n, '-')) {
$decimals = strlen(substr($n, 0, $p - 1));
$exponent = substr($n, $p + 1);
$decimals += !empty($exponent)?$exponent - 1: 0;
} else {
$decimals = strlen(substr($n, strpos($n, '.') + 1));
}
echo $n.'<br>'.sprintf('%.'.$decimals.'f', 1 * $n);
Imagine doing this without the function sprintf() .
Opinion
Finally, personal opinion, but without wanting to disparage anyone, I find it unnecessary to use at all just to make the code beautiful. It does not make sense to use cases where the format is static, for example. It would only be consuming unnecessary processes.
Example of situation where it becomes unnecessary
$ch = curl_init(sprintf("%s/pages/%s/metrics/%s/data.json", $BASE_URI, $PAGE_ID, $METRIC_ID));
It makes no difference if you make an organized and standardized concatenation.
$ch = curl_init($BASE_URI.'/pages/'.$PAGE_ID.'/metrics/'.$METRIC_ID'./data.json');
As mentioned above, the format in this case is static. There is no need to use a dynamic formatting feature for something static.
$var1 = 'A';
$var2 = 'B';
$var3 = 'C';
echo $var1.''.$var2.''.$var3;
//Tempo: 596μs e algumas vezes a 610μs
// Não faz menor diferença usar vírgula ou ponto para concatenar.
$var1 = 'A';
$var2 = 'B';
$var3 = 'C';
echo sprintf('%1$s %2$s %3$s', $var1, $var2, $var3);
//Tempo: 786μs, porém, fica "flutuando" entre 880μs e 900μs
μs: microseconds
The difference for a single single line is 2 to 3 microseconds. Of course, for a single run it is irrelevant, but if the application takes the function to do all concatenations, somatize them. If you have 100 concatenations in the codes, it is no longer irrelevant. A loss of performance for an unnecessary "whim".
The examples have didactic purpose. They are merely illustrative.
