从字符串中删除尾随零

Question

I would like to remove trailing zero's according to the following rules:

• The input number will always have 4 decimal places
• The output number should always have between 2 and 4 decimals
• If the last two digits after the decimal is a zero, then remove both of them
• If the last digit after the decimal is a zero, then remove it

Examples:

• 1.0000 -> 1.00
• 1.4000 -> 1.40
• 1.4100 -> 1.41
• 1.4130 -> 1.413
• 1.4136 -> 1.4136

I have considered the following:

if (substr($number, -2) == '00') return substr($number, 0, 4);
if (substr($number, -1) == '0') return substr($number, 0, 5);
return $number;

Are there any better ways of doing this?

Answer 1

I think this should work:

return preg_replace('/0{1,2}$/', '', $number);

$strings = array ('1.4000', '1.4100', '1.4130', '1.4136', '1.4001', '1.0041');
foreach ($strings as $number) {
  echo "$number -> " . preg_replace('/0{0,2}$/', '', $number) . "\n";
}

Produces:

1.4000 -> 1.40
1.4100 -> 1.41
1.4130 -> 1.413
1.4136 -> 1.4136
1.4001 -> 1.4001
1.0041 -> 1.0041

Answer 2

Here's a variation on Barmar's solution that will work even if the input strings don't always have exactly 4 decimal places. It won't add missing zeroes, but it won't strip any more than it should either.

return preg_replace('/(\.[0-9]{2,}?)0*$/', '$1', $number);

As an example:

$strings = array(
    '1.4000',
    '1.4100',
    '1.4130',
    '1.4136',
    '1.0',
    '1.00',
    '1.000',
    '10000',
);
foreach ($strings as $number) {
    $fixed = preg_replace('/(\.[0-9]{2,}?)0*$/', '$1', $number);
    echo "{$number} -> {$fixed}\n";
}

Outputs:

1.4000 -> 1.40
1.4100 -> 1.41
1.4130 -> 1.413
1.4136 -> 1.4136
1.0 -> 1.0
1.00 -> 1.00
1.000 -> 1.00
10000 -> 10000

Answer 3

And now for something completely different...

<?php
$crlf = "\n";
$input = array('1.4000', '1.4300', '1.2340', '1.4012', '1.0034', '1.2', '1.23456');
foreach ($input as $in) {
  for($n = 4; $n>2; $n--) {
    $f1 = (float)round($in, $n);
    $f2 = (float)round($in, $n-1);
    if ($f1 !== $f2) break;
  }
  echo "for in = ".$in." out is ".number_format($in, $n) . $crlf;
}
?>

Output:

for in = 1.4000 out is 1.40
for in = 1.4300 out is 1.43
for in = 1.2340 out is 1.234
for in = 1.4012 out is 1.4012
for in = 1.0034 out is 1.0034
for in = 1.2 out is 1.20
for in = 1.23456 out is 1.2346

Note that this will behave as expected for properly formatted numbers (with exactly four digits after the decimal), but it will still behave when the numbers were not correctly formatted. Not quite what was asked for - but it's often better to have a robust solution than a minimalist one...