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php round after last decimal number

I want to convert numbers like below in php

EX1: 0.00004123456 => 0.00004 
EX2: 0.000000004123456 => 0.000000004
EX3: 2.04123456 => 2.04
EX4: 2.44123456 => 2.4

I did not get results from the round() and more solutions

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2

Answers


  1. 0

    Let’s do it as we would manually. Convert to string. Find a . and then the first non 0 char. substr then turn to number back.

    <?php


$number = 0.0001432323;
$number2 = 14.323232;
$number3 = -6.098;
$number4 = -6.09;
$number5 = 12;


function rounder($number)
{
    $str = (string) $number;
    $index_dot = strpos($str, ".");
    if ($index_dot === false) {
        return $number;
    }

    // find first non zero after the dot_index
    $index_first_non_zero = false;
    for ($i = $index_dot + 1; $i < strlen($str); $i++) {
        if ($str[$i] != "0") {
            $index_first_non_zero = $i;
            break;
        }
    }
    if ($index_first_non_zero === false) {
        return $number;
    }
    return (float) substr($number, 0, $index_first_non_zero + 1);
}

echo rounder($number) . "n";
echo rounder($number2) . "n";
echo rounder($number3) . "n";
echo rounder($number4) . "n";
echo rounder($number5) . "n";

    Output:

    0.0001
14.3
-6.09
-6.09
12
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  2. 0

    You can do it with a regex.

    function trimToFirst($number) {
    // this is done to handle the cases of scientific notation
    // which can mess up the logic with very small or very large
    // numbers
    $strNum = sprintf('%f',$number);
    preg_match('/^-?d+.?d*?([1-9].*?|0$)/',$strNum,$matches);
    
    if(empty($matches)) {
        return $number;
    } else {
        return (float)$matches[0];
    }
}

$numArr = [15, -7.130, 2.07014430, 0.00004123456, 0.0123456, 2.04123456, 2.44123456, .051, 0, -0, 0.000000];

foreach($numArr as $originalNumber) {
    $number = trimToFirst($originalNumber);
    if (strpos($number, '.') !== false) {
        // convert the number to a string format without scientific notation
        // and trim trailing zeroes
        echo rtrim(sprintf('%f', $number), '0');
    } else {
        // an integer, leave it as it is
        echo $number;
    }
    
    echo PHP_EOL;
}

    Which outputs:

    15
-7.1
2.07
0.00004
0.01
2.04
2.4
0.05
0
0
0

    Test it here.

    Explanation

    The regular expression which was used functions like this (as explained in this regex101.com snippet ):

    • ^ asserts position at start of a line
    • - matches the dash character
    • ? matches the previous dash between zero and one times. This is done to handle cases when there are both positive and negative integers
    • d matches a digit (equivalent to [0-9])
    • + matches the previous token between one and unlimited times, as many times as possible,
    • . matches the decimal point
    • ? matches the previous decimal point between zero and one times. This is used to handle cases when there are integers and decimal numbers
    • d as before, this matches a digit
    • *? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
    • ( and ) are used to denote our capturing group and all the possible alternatives
    • [1-9].*? – this is the first alternative. We’re matching all the digits that can come after a decimal point, which are not zero
    • 0$ – this is the second alternative. It’s for handling cases when a number is a zero only number
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