php转字符串的方法有哪些

$var = 123;
$str = "This is a string with number $var";

$var = 123;
$str = "This is a string with number " . $var;

$var = 123;
$str = sprintf("This is a string with number %d", $var);

$arr = array('Hello', 'World');
$str = implode(' ', $arr);

$arr = array('Hello', 'World');
$str = json_encode($arr);

$arr = array('Hello', 'World');
$str = serialize($arr);