<form id="frm" method="post" action="./example/">
        <input type="hidden" name="example" value="data">
        <button type="submit" class="btn btn-primary">Submit1</button>
    </form>
    <form method="post" action="./example/">
        <input type="hidden" name="example" value="data">
        <button id="btn" type="submit" class="btn btn-primary">Submit2</button>
    </form>    
    <form method="post" action="./example/" onsubmit="return func1()" >
        <input type="hidden" name="example" value="data">
        <button type="submit" class="btn btn-primary">Submit3</button>
    </form>
    <form method="post" action="./example/"  >
        <input type="hidden" name="example" value="data">
        <button type="submit" class="btn btn-primary" onclick="return func2()" >Submit4</button>
    </form>

//例１
document.getElementById("frm").addEventListener("submit",function(event){
    event.preventDefault();
});
//例２
document.getElementById("btn").addEventListener("click",function(event){
    event.preventDefault();
    event.stopPropagation();//インターフェイスのメソッドで、キャプチャおよびバブリング段階において現在のイベントのさらなる伝播を阻止します。 
});
//例３
function func1(){
    return false;
}
//例４
function func2(){
    return false;
}

<form action="rensou.php" method="POST">
    <input name="name" type="text"><br>
    <input name="name2" type="text"><br>
    <input name="name3" type="text"><br>
    <input name="name4" type="text"><br>
    <input name="name5" type="text"><br>
    <input name="name6" type="text"><br>
    <input name="name7" type="text"><br>
    <input type="submit"><br>
</form>
<?php
$_POST = xss_d($_POST);
$array = [];
if(is_array($_POST)){
    foreach ($_POST as $key => $value) {
        if($value<>""){
            $array[$key] = $value;
        }
    }
}
?>
連想配列表示<br>
<textarea style="width: 500px;height: 500px;">
<?php
print_r (count($array)>0)?($array):["値無し"];
?>
</textarea>

<?php
function xss_d($val){
    if(is_array($val)){
        foreach ($val as $key => $value) {
            # code...
            $val[$key] = strip_tags($value);
            $val[$key] = htmlentities($val[$key],ENT_QUOTES);
        }
    }else{

        $val = strip_tags($val);
        $val = htmlentities($val,ENT_QUOTES);        
    }
    return $val;
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Tamir.SharpSsh;
namespace ftp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            Sftp sftp = new Sftp("192.168.11.1", "id", "pass");
            sftp.Connect();
            sftp.Get("/www/html/hoge.mp4", "C:\\Users\\hoge\\Documents\\hoge.mp4");
            sftp.Close();
            MessageBox.Show("ｷﾀ━━━━(ﾟ∀ﾟ)━━━━!!");
        }
    }
}