在php中使用double / float [重复]

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PHP: show a number to 2 decimal places

$b = $del['Antal'];
$y = $info['Pris'];
$z = $y * $b;

$y comes from a mysql database where its type is "double(10,2)" so that one works when I try echo $y; it responds with two decimals.

But now I would like to multiply it with $b.

For example 10.20 * 2 = 20.40

But right now it is like: 10.20 * 2 = 20.4 (only one decimal)

I want two decimals, what to do? I tried some stuff with the (double) function, but didn't really work out. What to do?

You can use number_format :

$b = $del['Antal'];
$y = $info['Pris'];
$z = number_format($y * $b ,2);

The number_format function :

string number_format ( float $number [, int $decimals = 0 ] )

And if you don't want the default format :

string number_format ( float $number , int $decimals = 0 , string $dec_point = '.' , string $thousands_sep = ',' )

Try floatval:

$z = $y * floatval($b);

Alternatively:

$b = (float) $b;

It should automatically convert to a float, however, if you multiply it by 10.20. Read PHP's documentation on type juggling.

If it's merely a styling thing:

$b = number_format($b, 2);

You can ensure that you store it at two decimal places by using sprintf and storing it as a string:

$z = sprintf('%.2f', $y * $b);

The %.2f ensure that there are always two digits after the decimal point.

The data type you describe are fixed point numbers, not floating point numbers (float). PHP does not have such a data type, however it can format floats for you. And it seems like that is what you are looking for, formatting output.