Random rnd = new Random();
dataGridView1.Rows[i].Cells[j].Value = r.Next(0, 10+1);
(int)numericUpDown1.Value;

int le = sor.Length;
String mondat = sor.Substring(0, le - 1);

class SzTorta : Torta
    {
        public int gyertya { get; set; }
        public SzTorta(int szelet, string iz, int gyertya)
            : base(szelet, iz)
        {
            this.szelet = szelet;
            this.iz = iz;
            this.gyertya = gyertya;
        }}
	
List<int> t = new List<int>();
        struct villamos
        {
            public int tav;
            public int erk;
            public int ind;
        }
		
StreamReader f;
    villamos[] t;
    if (openFileDialog1.ShowDialog() == DialogResult.OK)
        {
        f = new StreamReader(openFileDialog1.FileName);
        //int n = Convert.ToInt32(f.ReadLine());
        string[] sz = f.ReadLine().Split(' ');
        int n = Convert.ToInt32(sz[0]);
        int sa = Convert.ToInt32(sz[1]);
        t = new villamos[n];
        int i = 0;
        while (!f.EndOfStream)
            {
            //struktura
            sz = f.ReadLine().Split(' ');
            t[i].tav = Convert.ToInt32(sz[0]);
            t[i].erk = Convert.ToInt32(sz[1]);
            t[i].ind = Convert.ToInt32(sz[2]);
listBox2.Items.Add(t[i].tav+" "+  t[i].erk+" "+t[i].ind);
            i++;
            }
            f.Close();
			
StreamReader f;
    int[,] m;
    if (openFileDialog1.ShowDialog() == DialogResult.OK)
    {
        f = new StreamReader(openFileDialog1.FileName);
        string[] sz0 = f.ReadLine().Split(' ');
        int x = Convert.ToInt32(sz0[0]);
        int y = Convert.ToInt32(sz0[1]);
        m = new int[x+2, y];
        int j = 0;
        while (!f.EndOfStream)
            {
            string sor = "";
            int[] sz;
sz = Array.ConvertAll(f.ReadLine().Split(' '), Convert.ToInt32);
            for (int i = 0; i < y; i++)
                {
                m[j, i] = sz[i];
                sor += m[j, i] + " ";
                }
            listBox3.Items.Add(sor);
            j++;
                }
            f.Close();
            }
			
class Aritmatika
    {
    int[,] t;
    int a { get; set; }// public
    int b { get; set; }// public
    public Aritmatika()
        {
        //üres konstruktor nev ugyanaz mint osztály
        a = 0;//alapértékek
        b = 0;	}
    public Aritmatika(int szam1, int szam2)
        {
        t = new int[8, 8];
        this.a = szam1;//this ha szam1 szintén a  nev ugyanaz mint osztály
        this.b = szam2;}
    public Aritmatika(int szam1	{
        a = szam1;
        b = szam1;}
    //metódus
    public int Osszead(){	{
        return a + b; }

int result;         
if (int.TryParse(textBox1.Text, out result)){
    double t = Convert.ToInt32(textBox1.Text) * 1.27;
    textBox2.Text = Convert.ToString(t);
    textBox3.Text = Convert.ToString(result);}
else {MessageBox.Show("NaN");}// try catch is jó

toolStripMenuItem1.Text = "Save";
toolStripMenuItem2.Text = "Open";
private void toolStripMenuItem1_Click(object sender, EventArgs e){
//SaveFileDialog saveFileDialog1 = new SaveFileDialog();
saveFileDialog1.Filter = "txt|*.txt";
saveFileDialog1.Title = "Save a txt File";
saveFileDialog1.InitialDirectory = "C:/Users/FDPeter/Desktop";
saveFileDialog1.ShowDialog();
if (saveFileDialog1.FileName != ""){
StreamWriter w = new StreamWriter(saveFileDialog1.FileName);
w.WriteLine("ok");
w.Close();}}

ALTER TABLE anyag
ADD ertek INT(11);

DELIMITER $$
CREATE PROCEDURE randanyag()	
BEGIN 
DECLARE rnd INT;
SET rnd = FLOOR(RAND()*(401)+100);
UPDATE anyag SET ertek = rnd;
END	
CALL randanyag();

DELIMITER $$
CREATE FUNCTION howgram(id DOUBLE) RETURNS VARCHAR(20)
DETERMINISTIC
BEGIN
DECLARE hanygram varchar(20);
DECLARE gram double;
SELECT tomeg INTO gram FROM erme WHERE ermeid = id ;
SET hanygram = gram;
RETURN (hanygram);
END
SELECT `howgram`(2);

CREATE VIEW list AS
SELECT erme.cimlet, erme.darab, (`howgram`(erme.ermeid)* anyag.ertek/1000) 
koltseg FROM erme 
INNER JOIN
anyag ON anyag.femid = erme.ermeid

INSERT INTO tervezo(tid,nev) VALUE(8,'Anonymus');

DELIMITER $$
CREATE TRIGGER tervezodel 
    BEFORE DELETE ON tervezo
    FOR EACH ROW 
BEGIN
	UPDATE tkod
	SET tervezoid = 8
	WHERE tkod.tervezoid = OLD.tid;
END$$
DELIMITER;

PRIMARY KEY (OrderID),
    CONSTRAINT FK_PersonOrder FOREIGN KEY (PersonID)
    REFERENCES Persons(PersonID)

SELECT DISTINCT FROM WHERE GROUPBY HAVING ORDERBY 

function createTable() {  
var rn =10; var cn =10;
for(var r=0;r<=rn;r++)  {  
var x=document.getElementById('myTable').insertRow(r);  
for(var c=0;c<=cn;c++) {  
var y=  x.insertCell(c);  
y.innerHTML=" ";}  }  }  
<body onload = "createTable()">   
<table id="myTable"> </table>

var doboz= document.getElementById("doboz");
for(var i = 0; i<n; i++){
d = document.createElement("img");
d.src='kep.jpg';
doboz.appendChild(d);}
div id="doboz"></div>

var kepek=["k1.png","k2.png","k3.png"];
var i = 0;var kep="";
function tovabb() {
i++;
if(i>2)i=0;
srckep="image/"+kepek[i];
document.getElementById("kept").innerHTML="<img src="+srckep+" 
alt='képek' title = 'képek'/>";
console.log(i);}
function vissza() {
i--;
if(i<0) i = kepek.length-1;
srckep="image/"+kepek[i];
document.getElementById("kept").innerHTML="<img src="+srckep+" 
alt='kepek'  title = 'képek'/>";
console.log(srckep);}
function ellenoriz() {
var dn=0;var nev="";var email="";
dn=document.getElementById("menny").value;
.....
if(dn>=10){
alert('Kedves '+nev+' Megr Az e ' 
+email+ ' címre');}
else{
alert("a minimális 10 darabszámot!");}}


<h1>Emlékérmék</h1>
<div id="kepnezegeto">
<table >
<tr>
<td onclick = "vissza()">Vissza</td>
<td id = "kept"> <img src="./image/k1.png" alt = "k1" title = "k1"></td>
<td onclick = "tovabb()">Előre </td>
</tr>
</table>
</div>


<?php
class Ermek {
private $arr=array();
function __construct() {
include("controller/dbconnect.php");
$sql="SELECT * FROM erme";
$result=$db->query($sql);
$r = mysqli_num_rows($result);
for($i=0; $i<$r; $i++){
$this->arr[$i]=mysqli_fetch_assoc($result);}}
public function isForgalomban($sor) {
	return $sor["bevonas"]!="";}
public function getErmekDB(){
	return sizeof($this->arr);}
public  function getErmeInfo($sor, $mezo){
	return $this->arr[$sor][$mezo];}}
?>

<?php
$a= new Ermek();
$m = $a->getErmekDB();
echo'<table>';
echo '<thead><tr><td> cimlet</td>...</tr></thead>';
for($i=0;$i<$m;$i++){
echo '<tbody>';
echo '<tr>';
echo '<td>';
echo $a->getermeinfo($i,"cimlet");
echo '</td>';
........
echo '</tr>';
echo '</tbody>';}
echo'</table>';
?>

<h1>Rendelés</h1>
<div class="form-group">
<label for="nev">Név</label><input type="text" class="form-control" 
placeholder="Név" id="nev">
......
<select multiple class="form-control" id="erme">
<option value="1">2018</option>
.....
</select>
<label for="menny">Mennyiség</label><input type="number" 
class="form-control" placeholder="Mennyiség" id="menny" value="10" 
min="1" max="1000">
<br/>
<button class="btn btn-success" onclick="ellenoriz()"> Megrendelem!</button>
</div>