在php中添加前导0

Question

I have

• tutorial 1 how to make this
• tutorial 21 how to make this
• tutorial 2 how to make this
• tutorial 3 how to make this

and i need

• tutorial 01 how to make this
• tutorial 21 how to make this
• tutorial 02 how to make this
• tutorial 03 how to make this

so i can order them properly. (adding leading 0 when single digit is found)

What would be a php method to convert?

thanks in advance

note-please make sure that it identifies the single digit numbers only first and then add the leading zero

Answer 1

str_pad()

echo str_pad($input, 2, "0", STR_PAD_LEFT);

sprintf()

echo sprintf("%02d", $input);

Answer 2

If it is coming from a DB, this is the way to do it on a sql query:

lpad(yourfield, (select length(max(yourfield)) FROM yourtable),'0') yourfield

This is will get the max value in the table and place the leading zeros.

If it's hardcoded (PHP), use str_pad()

str_pad($yourvar, $numberofzeros, "0", STR_PAD_LEFT);

This is a small example of what I did on a online php compiler, and it works...

$string = "Tutorial 1 how to";

$number = explode(" ", $string); //Divides the string in a array
$number = $number[1]; //The number is in the position 1 in the array, so this will be number variable

$str = ""; //The final number
if($number<10) $str .= "0"; //If the number is below 10, it will add a leading zero
$str .= $number; //Then, add the number

$string = str_replace($number, $str, $string); //Then, replace the old number with the new one on the string

echo $string;

Answer 3

If your goal is to do natural ordering, the way a human being would, why not just use strnatcmp

$arr = [
    'tutorial 1 how to make this',
    'tutorial 21 how to make this',
    'tutorial 2 how to make this',
    'tutorial 3 how to make this',
];
usort($arr, "strnatcmp");
print_r($arr);

The above example will output:

Array
(
    [0] => tutorial 1 how to make this
    [1] => tutorial 2 how to make this
    [2] => tutorial 3 how to make this
    [3] => tutorial 21 how to make this
)