How to automatically complete the number of digits in a number or string in php

//Generate 4 digits, add 0 if necessary
$var=sprintf("%04d", 2);
echo $var;//The result is 0002
echo date(' y_m_d', time()).'_'.sprintf('d', rand(0,99));
?>

sprintf() function Does it feel like C language? 1. Grammar sprintf(format,arg1,arg2,arg++) Parameter Description format required. Convert format. arg1 required. Specifies the parameters to be inserted at the first % sign in the format string. arg2 optional. Specifies the parameter to be inserted into the format string at the second % sign. arg++ Optional. Specifies the parameters to be inserted into the format string at the third, fourth, etc. % symbols.

2, Description (edited and organized by bbs.it-home.org Script School)

$number = 123;
$txt = sprintf("%f",$number);
echo $txt;
?>

3, Format number number_format()

$number = 1234.56;
// english notation (default)
$english_format_number = number_format($number);
/ / 1,235
// french notation
$nombre_format_francais = number_format($number, 2, ',', ' ');
// 1 234,56

// english notation without thousands seperator
$english_format_number = number_format($number, 2, '.', '');
// 1234.57
?>