Question

Sprintf code explanation

Asked by: allanch08

Hello experts.

I have a simple piece of code that I need help being explained. I've checked the php manual but still can't decipher it.

echo sprintf("%1\$.1f", 3.141);

The ouput is 3.1

I know the $.1f treats it as a floating point number but what does the %1 do exactly?

I also if I want to round the number to just 3 would this be correct:

sprintf("%1\$u", 3.141)

thanks

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Asked On
2008-09-14 at 13:29:43ID23730451
Tags

PHP

Topic

PHP and Databases

Participating Experts
1
Points
250
Comments
9

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Answers

 

by: pzurowskiPosted on 2008-09-14 at 13:35:45ID: 22474186

%n is parameter placement, see code below. If you want to round to just 3, use "%.0f"

<?php
$format = 'The %2$s contains %1$d monkeys.
           That\'s a nice %2$s full of %1$d monkeys.';
printf($format, $num, $location);
?>

                                              
1:
2:
3:
4:
5:

Select allOpen in new window

 

by: allanch08Posted on 2008-09-14 at 13:43:23ID: 22474221

okay so when you mean parameter placement its like assigning a variable?

So does are these statments just the same:

%1\$.1f

and

%1\$u

 

by: allanch08Posted on 2008-09-14 at 13:44:18ID: 22474224

sorry I meant

%1\$.0f

and

%1\$u

 

by: pzurowskiPosted on 2008-09-14 at 13:52:41ID: 22474272

i think there will be no visible difference

from manual:
u - the argument is treated as an integer, and presented as an unsigned decimal number.
f - the argument is treated as a float, and presented as a floating-point number (...)

if you have only one argument to place, use "%d", "%u" or "%.0f". (d is like u but signed decimal)

 

by: allanch08Posted on 2008-09-14 at 14:03:34ID: 22474308

that's cleared up the second bit thanks.

so if I only have one argument do i need the %1

can i just have

echo sprintf("%u", 3.141)

as opposed to

echo sprintf("%1\$u", 3.141)

 

by: pzurowskiPosted on 2008-09-14 at 14:05:12ID: 22474314

yes, you can

 

by: allanch08Posted on 2008-09-14 at 14:26:11ID: 22474407

and if i have three arguments then I'd have to use %1, %2 and 5 3 to diffrentiate them?

 

by: allanch08Posted on 2008-09-14 at 14:26:43ID: 22474412

sorry

and if i have three arguments then I'd have to use %1, %2 and %3 to diffrentiate them?

 

by: pzurowskiPosted on 2008-09-14 at 14:47:38ID: 22474519

no, you don't have to

sprintf( 'a=%s, b=%s, a=%s', a, b, a )

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