PHP does not allow users to submit empty forms (php empty value judgment)_PHP tutorial

You can modify the code and add some judgment:

Copy code The code is as follows:

if(empty($_POST['name'])){
echo "As the saying goes, when a wild goose passes by, it leaves behind a voice and a person leaves behind a name
";
}

elseif(empty($_POST['comment'])){
echo "Hey, please say a few more words~";
}
else{
$sql = "INSERT INTO myblog_comments(blog_id, dateposted, name, comment) VALUES(" . $validentry . ", NOW(), '" . $_POST['name'] . "', '" . $_POST['comment'] . " ');";
mysql_query($sql);
header("Location: http://". $_SERVER['HTTP_HOST'] . $_SERVER['SCRIPT_NAME']."?id=" . $validentry);
}

PHP null value judgment

Although empty and isset are both variable processing functions, they are both used to determine whether the variable has been configured, but they have certain differences: empty will also detect whether the variable is empty or zero. When a variable value is 0, empty considers the variable to be equivalent to being empty, which is equivalent to not being set.

Copy code The code is as follows:

/*For example, to detect the ＄id variable, when ＄id =0, use empty and isset to detect whether the variable $id has been configured. Both will return different values ​​- empty thinks there is no configuration, isset can get the value of $id: */
$id=0;
empty(＄id)?print "It's empty .":print "It's ＄id .";
//Result: It's empty .
print "
";
!isset( ＄id)?print "It's empty .":print "It's ＄id .";
//Result: It's 0 .
?>

To summarize, "NULL" and "empty" are two concepts in PHP.

isset is mainly used to determine whether a variable has been initialized.
empty can judge variables with values ​​of "false", "empty", "0", "NULL" and "uninitialized" as TRUE
is_null Only variables with a value of "NULL" are judged as TRUE
var == null Judge variables with a value of "false", "empty", "0", and "NULL" as TRUE
var === null Only variables with a value of "NULL" are judged as TRUE
So when we judge whether a variable is really "NULL", we mostly use is_null to avoid "false", "0" and other values. interference.

http://www.bkjia.com/PHPjc/825197.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/825197.htmlTechArticleYou can modify the code and add some judgments: Copy the code as follows: if(empty($_POST['name'] )){ echo "As the saying goes, when the geese pass by, the people who leave their names will leave their namesbr /"; } elseif(empty($_POST['comment'...