How to force PHP to output a number preceded by zeros?

Question

for ($number = 1; $number <= 16; $number++) {
    echo $number . "\n";
}

This code outputs:

1
2
3
...
16

How can I get PHP to output the numbers preceded by zeros?

Pascal MARTIN · Accepted Answer · 2010-02-18T19:02:04.793

You could use sprintf to format your number to a string, or printf to format it and display the string immediatly.

You'd have to specify a format such as this one, I'd say : %02d :

padding specifier = 0
width specifier = 2
integer = d

(Even if you have what you want here, you should read the manual page of sprintf : there are a lot of possibilities, depending on the kind of data you are using, and the kind of output formating you want)

And, as a demo, if temp.php contains this portion of code :

<?php
for ($number = 1; $number <= 16; $number++) {
    printf("%02d\n", $number);
}

Calling it will give you :

C:\dev\tests\temp>php temp.php
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16

score 5 · Answer 2 · edited Jun 20 '20 at 09:12

5

You can use str_pad().

str_pad — Pad a string to a certain length with another string

This functions returns the input string padded on the left, the right, or both sides to the specified padding length. If the optional argument pad_string is not supplied, the input is padded with spaces, otherwise it is padded with characters from pad_string up to the limit.

edited Jun 20 '20 at 09:12

Community

1
1

answered Feb 18 '10 at 18:55

Pekka

442,112
142
972
1,088

score 4 · Answer 3 · answered Feb 18 '10 at 18:56

4

The old-fashioned way: $str = sprintf("%02.2d", $number); or use printf("%02.2d\n", $number); to print it immediately.

answered Feb 18 '10 at 18:56

Chris

136
2

score 3 · Answer 4 · answered Feb 18 '10 at 19:02

3

for ($number = 1; $number <= 16; $number++) {
  echo sprintf("%02d", $number) . "<br>";
}

answered Feb 18 '10 at 19:02

Keith Maurino

3,374
10
40
48

score 0 · Answer 5 · answered Feb 18 '10 at 18:55

0

if($number < 10) echo '0' . $number;

I know there are a lot better answers than this here, but I though't I'd leave it to show there's more than one way to skin a cat...

answered Feb 18 '10 at 18:55

Skilldrick

69,215
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This needs an else branch. Otherwise numbers > 10 aren't printed at all. – VolkerK Feb 18 '10 at 18:58
I know. I assumed that Andrew would be able to work out the rest... It's just meant to be a snippet. – Skilldrick Feb 18 '10 at 18:59

score 0 · Answer 6 · answered Feb 18 '10 at 18:57

0

Quick method:

<?php
for ($number = 1; $number <= 16; $number++)
{    
    if($number < 10)
        echo "0".$number."\n";
    else
        echo $number."\n";
}
?>

answered Feb 18 '10 at 18:57

Urda

5,460
5
34
47

I'm going to go out on a limb here, I don't think efficiency is OP's highest worry. But hey it was just a simple answer for a simple question. Sorry your nose is too high up in the clouds at this point though! – Urda Feb 19 '10 at 01:51

score 0 · Answer 7 · answered Feb 18 '10 at 19:48

0

Lets keep it simple. Use str_pad

echo str_pad(1, 6 , "0");

produces 000006

answered Feb 18 '10 at 19:48

ronaldosantana

5,112
4
22
28

score 0 · Answer 8 · answered Aug 06 '16 at 16:01

0

echo ($number < 10) ? (0 . $number) : $number;

answered Aug 06 '16 at 16:01

user2666261

16

score -1 · Answer 9 · edited Feb 18 '10 at 18:59

-1

<?php
  for ($number = 1; $number <= 16; $number++) 
  { 
    if($number<10)
      echo '0';
    echo $number . "<br>"; 
  }
?>

edited Feb 18 '10 at 18:59

VolkerK

95,432
20
163
226

answered Feb 18 '10 at 18:56

Dave

1,065
2
10
16

That would give you 010, 011, 012, etc. – Sean Bright Feb 18 '10 at 18:57
1

please use ctrl+k to mark code blocks (or indent the code manually with 4 spaces) – VolkerK Feb 18 '10 at 19:00
1

you see how the printf approach is superior, I hope? – Sean Bright Feb 18 '10 at 19:04
absolutely, much cleaner code! I didn't know about str_pad(), which seems really handy. – Dave Feb 18 '10 at 23:08

How to force PHP to output a number preceded by zeros?

9 Answers9