Safe Casting Functions RFC conversions table generator (see: https://wiki.php.net/rfc/safe_cast)

make_table.php

<?php

class NotStringable {}
class Stringable {
    public function __toString() {
        return "foobar";
    }
}

$values = [
    "foobar",
    "",
    "0",
    0,
    0.0,
    "10",
    "010",
    "+10",
    "-10",
    10,
    10.0,
    (string)PHP_INT_MAX,
    PHP_INT_MAX,
    (string)PHP_INT_MIN,
    PHP_INT_MIN,
    "10.0",
    "75e-5",
    "31e+7",
    NULL,
    TRUE,
    FALSE,
    new StdClass,
    fopen("data:text/html,foobar", "r"),
    [],
    1.5,
    "1.5",
    "10abc",
    "abc10",
    "100 ",
    " 100",
    " 100 ",
    "0x10",
    INF,
    -INF,
    NAN,
    PHP_INT_MAX * 2,
    PHP_INT_MIN * 2,
    (string)(PHP_INT_MAX * 2),
    (string)(PHP_INT_MIN * 2),
    new Stringable,
    new NotStringable,
    new StdClass
];

function var_dump_string($var) {
    ob_start();
    var_dump($var);
    $result = ob_get_clean();
    return preg_replace('/\s{2,}/', ' ', preg_replace('/[\n\r]/','',rtrim($result)));
}

$functions = [
    NULL,
    'to_int',
    'to_float',
    'to_string'
];

// functions which cast to and back to see if data lost
$alt_functions = [
    NULL,
    function ($val) {
        $newval = $val;
        $type = gettype($val);
        settype($newval, 'integer');
        settype($newval, $type);
        if ($newval === $val) {
            return (int)$val;
        } else {
            return NULL;
        }
    },
    function ($val) {
        $newval = $val;
        $type = gettype($val);
        settype($newval, 'double');
        settype($newval, $type);
        if ($newval === $val) {
            return (float)$val;
        } else {
            return NULL;
        }
    },
    function ($val) {
        $newval = $val;
        $type = gettype($val);
        settype($newval, 'string');
        settype($newval, $type);
        if ($newval === $val) {
            return (string)$val;
        } else {
            return NULL;
        }
    }
];

$columnWidth = 40;

echo '^ ';
foreach ($functions as $function) {
    if ($function === NULL) {
        echo str_pad('value', $columnWidth);
    } else {
        echo str_pad($function, $columnWidth);
    }
    echo '^ ';
}
echo PHP_EOL;

foreach ($values as $value) {
    echo '^ ';
    foreach ($functions as $i => $function) {
        $alt_function = $alt_functions[$i];
        if ($function === NULL) {
            echo str_pad(var_dump_string($value), $columnWidth);
        } else {
            $result = $function($value) === NULL ? 'fail' : 'pass';
            //$result .= '/' . ($alt_function($value) === NULL ? 'fail' : 'pass');
            echo str_pad($result, $columnWidth);
        }
        echo '| ';
    }
    echo PHP_EOL;
}