function call is not working

PHP is not able to call a function properly.
Calling like this does not display an error message and
Empty data will be displayed.
If there is a value, it is correct to send it like this, but
https://i.stack.imgur.com/1SiBK.png
I want to display an error message when there is no value, but it is normally registered as empty data.
https://i.stack.imgur.com/IQyKc.png
By the way, the functions I want to call are check_name() and check_comment().
How can I call them?
Please let me know.

source code
<?php

define('DB_HOST', '); // Hostname or IP address of the database
define('DB_USER', '); // MySQL username
define('DB_PASSWD', '); // MySQL password
define('DB_NAME', '); // database name

define('HTML_CHARACTER_SET', 'UTF-8');
define('DB_CHARACTER_SET', 'UTF8');

date_default_timezone_set('Asia/Tokyo');
$errors=array();
$insert_datas=[];
$select_datas=[];

// db connection
 $link = get_db_connect();
 
 $insert_datas=insert_sql($link);
 
 $select_datas=select_sql($link); 
 
 close_db_connect($link);
 
 //entity_assoc_array($datas);
 

function get_db_connect(){
    // Get Connection
    if(!$link=mysqli_connect(DB_HOST, DB_USER, DB_PASSWD, DB_NAME)){

        die('error:'.mysqli_connect_error());
    }

    // Character Code Set
    mysqli_set_charset($link,DB_CHARACTER_SET);

    return$link;
}

function get_as_array($link,$sql){
 
    // return sequence
    $data=[];
 
    // execute a query
    if($result=mysqli_query($link,$sql))}
 
        if(mysqli_num_rows($result)>0){
 
            // take out one by one
            while($row=mysqli_fetch_assoc($result)){
                $data[] = $row;
            }
 
        }
 
        // Open result set
        mysqli_free_result($result);
 
    }
 
    return$data;
 
}

function insert_sql($link){
    if(isset($_POST['send'])===true){
    $error1 = check_name();
    $error2 = check_comment();
    if($error1==="||$error2===""){
    $name = $_POST ['name'];
    $comment=$_POST ['comment'];
    $date=date("Y-m-d H:i:s");
    $sql = 'INSERT INTO comment_table(name, comment, date)VALUES(\'.$name.'\', \'.$comment.'\', \'.$date.'\')';
    $result=mysqli_query($link,$sql);      
    return$result;
    }
}

}

function select_sql($link){

    $sql = 'SELECT name, comment, date FROM comment_table ORDER BY date DESC';

    return get_as_array($link,$sql);
}

function close_db_connect($link){

    mysqli_close($link);
}
function check_name(){ 
        if(mb_strlen($_POST['name'])===""){
           $errors['name'] = 'Please enter a name';
        }  elseif(mb_strlen($_POST['name'])>20){
           $errors['name'] = 'Name must be up to 20 characters long';
        } else{
            $errors=";
        }
    return$ errors;
      }


function check_comment(){
        if(mb_strlen($_POST['comment'])===""){
           $errors['comment'] = 'Please enter a word';
        } elseif(mb_strlen($_POST['comment'])>100){
           $errors['comment'] = 'Please enter up to 100 characters per word';
        } else{
            $errors=";
        }
    return$ errors;
}

/* functionality_str($str){
    return html specialchars($str,ENT_QUOTES,HTML_CHARACTER_SET);
}

functionality_assoc_array($assoc_array){
 $assoc_array=[];
    foreach($asoc_array as$key=>$value){
 
        foreach($value as$keys=>$values){
            $assoc_array[$key][$keys]=entity_str($values);
        }
 
    }
 
    return$assoc_array;
 
}*/

?>
<!DOCTYPE html>
<html lang="ja">
<head>
    <metacharset="UTF-8">
    <title> </title>
</head>
<body>
    <h1>One word bulletin board</h1>
    <form method="post">
         <?php if(count($errors)>0){?>
         <ul>
          <?php foreach($errors as$value){?>
        <li><?phpechohtmlspecialchars($value,ENT_QUOTES,'UTF-8');?></li>
         <?php}?>
         </ul>
           <?php}?>
        <p>Name:
            <input type="text" name="name">
            One word:
            <input type="text" name="comment" size="60">
            <input type="submit" name="send" value="send">
        </p>
    </form>

    <ul>
        <?php if(!empty($select_datas)){?>
        <?php foreach(array)$select_datasas$hitokoto){?>
            <li>
                <?php echo htmlspecialchars($hitokoto['name'], ENT_QUOTES, 'UTF-8');?>
                <?php echo htmlspecialchars($hitokoto['comment'], ENT_QUOTES, 'UTF-8');?>
                <?php echo htmlspecialchars($hitokoto['date'], ENT_QUOTES, 'UTF-8');?>
            </li>
        <?php}?>
        <?php}?>
    </ul>
</body>
</html>

php

2022-09-30 13:54

1 Answers

The mb_strlen conditional statement below is not working as designed.

 if(mb_strlen($_POST['name'])===""){

If you look at the mb_strlen documentation, you will see

mb_strlen(string$string, string | null$encoding=null): int

Therefore, the return value must return int.

However, since the condition is ===", we are comparing empty characters with int, so it is unlikely that this condition will be met.
If you want to compare the length of a multi-byte character to zero,

 if(mb_strlen($_POST['name'])===0){

If you simply want to check if it's empty, you can do the following.

 if($_POST['name']===""){

2022-09-30 13:54

If you have any answers or tips

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