练习使用session_start（）

Question

Should I use

session_start()

or

if (session_id() == ""){
  session_start();
}

because I remember correctly that without the latter there will be another error message?

Answer 1

Recommended way for versions of PHP >= 5.4.0

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

Source: http://www.php.net/manual/en/function.session-status.php

For versions of PHP < 5.4.0

if(session_id() == '') {
    session_start();
}

Both of these should work for what you are asking for.