检查PHP会话是否已经开始

#1 楼

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

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

#2 楼

if(session_id() == '') {
    // session isn't started
}

#3 楼

 session_id('test');
var_export(session_id() != ''); // true, but session is still not started!
var_export(session_status() == PHP_SESSION_ACTIVE); // false
 

 session_status() == PHP_SESSION_ACTIVE
 

#4 楼

#5 楼

if (version_compare(phpversion(), '5.4.0', '<')) {
     if(session_id() == '') {
        session_start();
     }
 }
 else
 {
    if (session_status() == PHP_SESSION_NONE) {
        session_start();
    }
 }

#6 楼

var_dump($_SESSION); // null
session_start();
var_dump($_SESSION); // array
session_destroy();
var_dump($_SESSION); // array, but session isn't active.

#7 楼

if ((function_exists('session_status') 
  && session_status() !== PHP_SESSION_ACTIVE) || !session_id()) {
  session_start();
}

#8 楼

<?php
/**
* @return bool
*/
function is_session_started()
{
    if ( php_sapi_name() !== 'cli' ) {
        if ( version_compare(phpversion(), '5.4.0', '>=') ) {
            return session_status() === PHP_SESSION_ACTIVE ? TRUE : FALSE;
        } else {
            return session_id() === '' ? FALSE : TRUE;
        }
    }
    return FALSE;
}

// Example
if ( is_session_started() === FALSE ) session_start();
?>

#9 楼

if (strlen(session_id()) < 1) {
    session_start();
}

#10 楼

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

#11 楼

function start_session() {
  if(version_compare(phpversion(), "5.4.0") != -1){
    if (session_status() == PHP_SESSION_NONE) {
      session_start();
    }
  } else {
    if(session_id() == '') {
      session_start();
    }
  }
}

#12 楼

<?php
if(!isset($_SESSION))
{
session_start();
}
?>

#13 楼

#14 楼

    <?php 
        if (session_status() !== PHP_SESSION_ACTIVE || session_id() === ""){
            session_start(); 
        }
    ?>

#15 楼

if(!strlen(session_id())){
    session_name('someSpecialName');
    session_start();
} 

#16 楼

    // PHP_VERSION_ID is available as of PHP 5.2.7, if our
    // version is lower than that, then emulate it
    if (!defined('PHP_VERSION_ID')) {
        $version = explode('.', PHP_VERSION);

        define('PHP_VERSION_ID', ($version[0] * 10000 + $version[1] * 100 + $version[2]));


        // PHP_VERSION_ID is defined as a number, where the higher the number
        // is, the newer a PHP version is used. It's defined as used in the above
        // expression:
        //
        // $version_id = $major_version * 10000 + $minor_version * 100 + $release_version;
        //
        // Now with PHP_VERSION_ID we can check for features this PHP version
        // may have, this doesn't require to use version_compare() everytime
        // you check if the current PHP version may not support a feature.
        //
        // For example, we may here define the PHP_VERSION_* constants thats
        // not available in versions prior to 5.2.7

        if (PHP_VERSION_ID < 50207) {
            define('PHP_MAJOR_VERSION',   $version[0]);
            define('PHP_MINOR_VERSION',   $version[1]);
            define('PHP_RELEASE_VERSION', $version[2]);

            // and so on, ...
        }
    }

    function phpVersionAtLeast($strVersion = '0.0.0')
    {
        $version = explode('.', $strVersion);

        $questionVer = $version[0] * 10000 + $version[1] * 100 + $version[2];

        if(PHP_VERSION_ID >= $questionVer)
            return true;
        else
            return false;

    }

    function openSession()
    {
        if(phpVersionAtLeast('5.4.0'))
        {
            if(session_status()==PHP_SESSION_NONE)
                session_start();
        }
        else // under 5.4.0
        {
            if(session_id() == '')
                session_start();
        }
    }

#17 楼

if (version_compare(PHP_VERSION, "5.4.0") >= 0) {
    $sess = session_status();
    if ($sess == PHP_SESSION_NONE) {
        session_start();
    }
} else {
    if (!$_SESSION) {
        session_start();
    }
}

#18 楼

if (!count($_SESSION)>0) {
    session_start();
}

#19 楼

#20 楼

session_start();
if(!empty($_SESSION['user']))
{     
  //code;
}
else
{
    header("location:index.php");
}

#21 楼

if (!defined('PHP_VERSION_ID')) {
    $version = explode('.', PHP_VERSION);
    define('PHP_VERSION_ID', ($version[0] * 10000 + $version[1] * 100 + $version[2]));
}else{
    $version = PHP_VERSION_ID;
}
if($version < 50400){
    if(session_id() == '') {
        session_start();
    }
}else{
    if (session_status() !== PHP_SESSION_ACTIVE) {
        session_start();
    }
}

#22 楼

#23 楼

if(session_status() !== PHP_SESSION_ACTIVE){session_start();};
if(session_status() !== PHP_SESSION_ACTIVE){die('session start failed');};

#24 楼

if(session_id()== '')
{
   echo"Session isn't Start";
}
else
{
    echo"Session Started";
}

#25 楼

if (empty($_SESSION)  && !isset($_SESSION))  {
    session_start();
}

#26 楼

if (!isset($a)) {
    a = False;
    if ($a == TRUE) {
        session_start();
        $a = TRUE;
    }
}