从字母数字字符串中提取数值而不使用任何预定义的函数

Question

I have a variable

$string  = "(123) 011 - 34343678";

and I want 12301134343678 as an output in integer data type. How can I do this without using any predefined function in PHP or in any other programming language.

Answer 1

Well it's not the nicest solution, but something like this could work for you:

Here I simply loop through all characters and check if they are still the same when you cast them to an integer and then back to a string. If yes it is a number otherwise not.

<?php

    function own_strlen($str) {
        $count = 0;
        while(@$str[$count] != "")
            $count++;
        return $count;
    }

    function removeNonNumericalCharacters($str) {
        $result = "";

        for($count = 0; $count < own_strlen($str); $count++) {
            $character = $str[$count];
            if((string)(int)$str[$count] === $character)
                $result .= $str[$count];
        }

        return $result;

    }

    $string  = "(123) 011 - 34343678";
    echo removeNonNumericalCharacters($string);

?>

output:

12301134343678

Answer 2

another solution

<?php
$str =  "15as55 - (011)";

$num_array = array();
for($i = 0;$i<=9;$i++)
{
$num_array[]=$i;    
}


for($coun_str = 0 ; isset($str[$coun_str]) && ($str[$coun_str] != "")  ; )
{
$coun_str++;    
}

$strlen = $coun_str - 1;


$outstr = "";
for($j=0;$j<=$strlen;$j++)
{

    foreach($num_array as $val)
    {
        if((string)$val == $str[$j])
        {
            $outstr .= $str[$j]; 


        }
    }




}
echo $outstr
?>

output : 1555011