Question

How to get the first digit of a float number in PHP

Answer 1

function get_first_digit($n) {
    $s = sprintf("%.4f", $n);
  
    return (int)$s[0];
}

$f = 239.5876;
$first_digit = get_first_digit($f);

echo $first_digit;   


/*
run:

2

*/

 

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Answer 2

function get_first_digit($f) {
    $first_digit = $f;

    while ($first_digit >= 9) {
        $first_digit = (int)($first_digit / 10);
    }
    
    return $first_digit;
}
  

$f = 761.7261;
  
echo get_first_digit($f);



  
/*
run:

7

*/

 

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Answer 3

function get_first_digit($f) {
    $total_digits_minus_one = (int)log10($f);

    $first_digit = (int)($f / pow(10, $total_digits_minus_one)); 
    
    return $first_digit;
}
  

$f = 9618.7261;
  
echo get_first_digit($f);



  
/*
run:

9

*/

 

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