php中的简单正则表达式，格式化十进制数

I need to convert numbers to have .00 after them, but only if the number is an integer, or it has just 1 number after the decimal point, like so:

1.4 = 1.40
45 = 45.00
34.77 = 34.77

What reg exp to use for this simple case?

number_format($number, 2, '.', '');

Read more at PHP.net. You don't need to determine if a number is an integer or not -- as long as it's a number, it will be formatted to two decimal places.

If you'd like the thousands separator, change the last parameter to ','.

Check out PHP's built-in function number_format

You can pass it a variable and it'll format it to the correct decimal places

    $number = 20;
    if (is_int($number)) {
        $number = number_format($number, 2, '.', '');
    }

read number_format

number_format($number, 2, '.', '');

You can also use printf or sprintf

printf("%01.2f", '34.77');
$formatted_num = sprintf("%01.2f", '34.77');

$num = 0.00638835;

$avg = sscanf($num,"%f")[0] /100;

echo sprintf("%.10f", $avg);

result 0.0000638835