[c#] 如何處理例外錯誤狀況 應用介紹-[try-catch-finally]

如何處理例外錯誤狀況 應用介紹-[try-catch-finally]

1.) NG程式
//錯誤程式,程式直接當掉(原因被除數不得維0)
private void button1_Click(object sender, EventArgs e)
{
int a = 0;
int b =100/a;
Console.WriteLine("b is {0}", b);
Console.WriteLine("End of job ");
}

2.) 攔截NG程式

//try-catch-finally語法(程式不會當掉,但提報錯誤)
private void button2_Click(object sender, EventArgs e)
{
int a = 0;
try
{
int b = 100 / a;
Console.WriteLine("b is {0}", b);
}
//錯誤攔截訊息
catch (Exception err1)
{
Console.WriteLine("Divided by zero ");
Console.WriteLine("Divided by zero {0}",err1 );
MessageBox.Show(err1.ToString ());
}
//最後一定會執行
finally
{
Console.WriteLine("End of job");
}

3.) 自行判斷NG錯誤跳轉攔截錯誤訊息(throw 使用)

//自行判斷錯誤跳轉攔截錯誤訊息(程式不會當掉,但提報錯誤)
private void button3_Click(object sender, EventArgs e)
{
int a = 100, b = 0;
try
{
if (b == 0)
{
//跳轉呼叫丟出錯誤
throw new ArithmeticException("Div by zero");
}
else
{
int c = a / b;
Console.WriteLine("Resoult is " + c);
}
Console.WriteLine("After divide2");
}
//
catch (ArithmeticException error)
{
Console.WriteLine("Caught!{0}",error );
}


===========================================
自訂錯誤類別-待續

[c#] String字串處理Split 應用介紹-[Split]

String字串處理Split 應用介紹-[Split]

//split
private void button_Click(object sender, EventArgs e)
{

char[] del = new char[] { ',','/' }; //多符號分離
//char del = ','; //單符號分離

string line = "datalog_mo1_0,2010/1/19下午 01:47:52,691,1,40197574905.7755";

string[] split = line.Split(del);

foreach (string s in split)
{
listBox1.Items.Add(s); //送到目標 listbox檢視
}

}

[SIEMENS SCL FC ] 由函式FC回傳演算計算 應用介紹-[SCL-FC ][IEC 61131-3]

由函式FC回傳演算計算 應用介紹-[SCL-FC][IEC 61131-3]


FUNCTION SQUARE : INT //帶回傳值

(*********************************************************

This function returns as its function value the square of the

input value or if there is overflow, the maximum value that

can be represented as an integer.

***********************************************************)

//know_how_protect //程式保護

//變數宣告in類型
VAR_INPUT

value : INT;

END_VAR

//程式開始
BEGIN

IF value <= 181 THEN

SQUARE := value * value; //計算含式

ELSE

SQUARE := 32_767; // overflow, 設定最大值並回傳當成錯誤碼

END_IF;

END_FUNCTION

[c#] 單一執行緒與委派 應用介紹-[Thread and Delegate]

單一執行緒與委派 應用介紹-[Thread and Delegate]

//產生紅色球球
bool flg1, flg2,flg3;

private void button1_Click(object sender, EventArgs e)
{

flg1 = true;
Thread th1 = new Thread(readtst);
th1.Start();

}

//執行緒目標
public void readtst()
{
while (flg1 == true)
{
textBox1.BeginInvoke(new creatball(rdball ));
Thread.Sleep(10);
}
}

//委派目標 (執行緒委派目標值傳回到form的物件)
private delegate void creatball( );
private void tst()
{
textBox1.AppendText("read ball" +DateTime .Now .ToLongTimeString ()+ "\n");
}

//委派目標 - 產生紅色球球
public void rdball()
{
Ball aBall;
aBall.pt = new Point(rd.Next(20, this.ClientSize.Width - 20), rd.Next(40, this.ClientSize.Height - 20));
aBall.color = Color.Red;

lock (this)
{
ballList.Add(aBall);
textBox1.AppendText("Read"+DateTime .Now .ToLongTimeString ()+ "\n");
}

this.Invalidate();
}

[c#] 由函式反向傳遞直給飲用者 應用介紹-[public void mystr(out string x)]

由函式反向傳遞值給引用者 應用介紹-[public void mystr(out string x)]

//函式引用者取值
private void button1_Click(object sender, EventArgs e)
{
string x;
mystr(out x);
textBox1.Text = x;
}

//反向送出函式
public void mystr(out string x)
{
x = "read";
Console.WriteLine(x);
}

[c#] delegate and winform object 應用介紹-[delegate]

delegate and winform object 應用介紹-[delegate]

//如何使用delegate把對象傳回到windows form

//傳回到windows form 物件
private void button1_Click(object sender, EventArgs e)
{
textBox1.BeginInvoke(new creatball(tst));
}

//委派對象
public delegate void creatball();
public void tst()
{
textBox1.AppendText("aaaa");
}

[c#] interface 應用介紹-[interface]

interface 應用介紹-[interface]


1.) interface 語法:


using System;using System.Collections.Generic;

using System.Text;


namespace areaFace

{
interface AreaInterface
{

void triangle(int x,int y); //三角形
int circle(int x, int y); //圓形 ,帶回傳值
void square(int x, int y); //方形
}
}

2.) interface實做:

using System;
using System.Collections.Generic;using System.Text;

namespace areaFace
{
public class AreaClass:AreaInterface
{
//圓circle面積公式: 圓面積=半徑×半徑×3.14
//正方形square面積公式: 長x寬＝正方
//梯形面積: 上底*高/2 +下底*高/2=(上底+下底)*高/2
//三角形triangle面積: 底×高÷２

//圓面積
private int circlradius1;
private int circlradius2;
public int circlarea;

//圓面積建構子
public AreaClass(int circlradius1, int circlradius2)
{
//呼叫圓面積涵式
circlarea = circle(circlradius1, circlradius2);
}

//圓面積實做
public int circle(int x ,int y)
{

//圓circle面積公式: 圓面積=半徑×半徑×3.14
int circlearea;
circlarea = x * y;
Console.WriteLine(circlarea); //打印

return circlarea; //回傳
}

public void square(int x, int y)
{
//未完
}

public void triangle(int x, int y)
{
//未完
}

}
}

3.) 實做測試:
using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;using System.Drawing;using System.Text;

using System.Windows.Forms;


namespace areaFace

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}


private void Form1_Load(object sender, EventArgs e)

{
AreaClass ar = new AreaClass(10, 20);

MessageBox.Show(ar.circlarea.ToString () );

}

}

}