Note that this also works with positional placeholders using the '?' token:

<?php

$stmt = $db->prepare('SELECT * FROM mytable WHERE foo = ? AND bar = ?');
$stmt->bindValue(1, 'somestring', SQLITE3_TEXT);
$stmt->bindValue(2, 42, SQLITE3_INTEGER);

?>

Positional numbering starts at 1.

I just want to say again, 

Numbering for parameters starts at ONE!

This has caught me out quite a few times!

It might be a good idea to feed bindValue the type of the variable manually, or you might encounter weird stuff as the passed value is often treated as SQLITE3_TEXT and results in buggy queries.

For example:
<?php
$st = $db->prepare('SELECT * FROM test WHERE (a+1) = ?');
$st->bindValue(1, 2);
?>

Will never return any result as it is treated by SQLite as if the query was 'SELECT * FROM test WHERE (a+1) = "2"'. Instead you have to set the type manually:

<?php
$st = $db->prepare('SELECT * FROM test WHERE (a+1) = ?');
$st->bindValue(1, 2, \SQLITE3_INTEGER);
?>

And it will work. This bug is reported in https://bugs.php.net/bug.php?id=68849

Here is a simple function to help you make bindValue work correctly:

<?php
function getArgType($arg)
{
    switch (gettype($arg))
    {
        case 'double': return SQLITE3_FLOAT;
        case 'integer': return SQLITE3_INTEGER;
        case 'boolean': return SQLITE3_INTEGER;
        case 'NULL': return SQLITE3_NULL;
        case 'string': return SQLITE3_TEXT;
        default:
            throw new \InvalidArgumentException('Argument is of invalid type '.gettype($arg));
    }
}
?>

I used following logic to prepare statements, It handles both Values and Arrays ( taking help from bohwaz note) :

<?php
    function getArgType($arg) {
        switch (gettype($arg)) {
            case 'double':  return SQLITE3_FLOAT;
            case 'integer': return SQLITE3_INTEGER;
            case 'boolean': return SQLITE3_INTEGER;
            case 'NULL':    return SQLITE3_NULL;
            case 'string':  return SQLITE3_TEXT;
            default:
                throw new \InvalidArgumentException('Argument is of invalid type '.gettype($arg));
        }
    }

foreach ($params as $index => $val) {
                // indexing start from 1 in Sqlite statement
                if (is_array($val)) {
                    $ok = $stmt->bindParam($index + 1, $val);
                } else {
                    $ok = $stmt->bindValue($index + 1, $val, getArgType($val));
                }
                
                if (!$ok) {
                    throw new Exception("Unable to bind param: $val");
                }
            }
?>