private void button1_Click(object sender, EventArgs e)
{
if (File.Exists(filename))
{
SelectFirstThree obj = new SelectFirstThree();
List <string> list = File.ReadAllLines(filename).ToList();
//findfirst3 是委派函式 委派找到檔案開頭為695 525的檔案
MyPredicate find = findfirst3;
var result = obj.DoWhere(list, find); //委派的list傳入 find委派函式
string st_date;
string TickNumber;
DateTime Flyingday;
DateTime Birthday;
foreach (var item in result)
{
st_date = item.Substring(0, 13);
TickNumber = st_date;
st_date = item.Substring(13, 8);
Flyingday = DateTime.ParseExact(st_date, "yyyyMMdd", null, System.Globalization.DateTimeStyles.AllowWhiteSpaces);
st_date = item.Substring(21, 8);
Birthday = DateTime.ParseExact(st_date, "yyyyMMdd", null, System.Globalization.DateTimeStyles.AllowWhiteSpaces);
InsertIntoDatabase(TickNumber, Flyingday, Birthday);
}
}
else
{
MessageBox.Show("找不到檔案");
}
}
public Task Test_Serialize_Predicate_Class()
{
IMyPredicate pred = new MyPredicate(_staticFilterValue2);
// Works OK
TestSerializePredicate("Predicate Class Instance", pred.FilterFunc);
return(Task.CompletedTask);
}
static void Main(string[] args)
{
MyPredicate pr0 = isPos;
//pr1 takes an int as a paerameter and returns bool
Predicate <int> pr1 = isPos;
Console.WriteLine(pr0(7));
Console.WriteLine(pr1(7));
}
/// <summary>
/// Перевірка чи відповідає хоч один елемент списку истиності певному твердженню
/// </summary>
/// <param name="condition">Предикат</param>
/// <returns></returns>
public bool Exist(MyPredicate <T> condition)
{
for (int i = 0; i < array.Length; i++)
{
if (condition.Invoke(array[i]))
{
return(true);
}
}
return(false);
}
// rather than re-writing the same code (almost), pass-in a "condition method"
// since we cannot pass a method to a method directly, we do that using
// a delegate object. we can pass a delegate object to a method, as a
// parameter using the type of condition method we want should have the signature
// of MyPredicate
static int Find(MyPredicate predicate) // need to associate 'predicate' with a method in order to invoke that method
{
foreach (int x in array)
{
if (predicate(x))
{
return(x);
}
}
return(0);
}
static uint MyCount(int[] arr, MyPredicate predic)
{
uint count = 0;
foreach (var item in arr)
{
if (predic(item))
{
++count;
}
}
return(count);
}
public static IList <T> Filter <T>(IList <T> source, MyPredicate <T> predicate)
{
List <T> ret = new List <T>();
foreach (T item in source)
{
if (predicate(item))
{
ret.Add(item);
}
}
return(ret);
}
public static int CountIf <T>(T[] a, MyPredicate <T> p)
{
int count = 0;
foreach (T i in a)
{
if (p(i))
{
++count;
}
}
return(count);
}
public List <string> DoWhere(List <string> source, MyPredicate predicate)
{
List <string> result = new List <string>();
foreach (var item in source)
{
if (predicate.Invoke(item))
{
result.Add(item);
}
}
return(result);
}
static public List <T> MyFindAll <T>(T[] arr, MyPredicate <T> predic)
{
List <T> elems = new List <T>();
foreach (var item in arr)
{
if (predic(item))
{
elems.Add(item);
}
}
return(elems);
}
static void Main(string[] args)
{
PreloadArray();
Display(array);
// find the first value that is positive
MyPredicate predicate = IsPositive;
int firstPosX = Find(predicate); // compiler creates a delegate to be passed to the Find() method
Console.WriteLine($"\n\nFirst positive value: { firstPosX }.");
// find the first value that is negative
predicate = IsNegative;
int firstNegX = Find(predicate);
Console.WriteLine($"\n\nFirst negative value: { firstNegX }.");
// find the first value that is negative and odd
predicate = IsNegativeOdd;
int firstNegOddX = Find(predicate);
Console.WriteLine($"\n\nFirst negative odd value: { firstNegOddX }.");
// find the first value that is positive and even
predicate = IsPositiveEven;
int firstPosEvenX = Find(predicate);
Console.WriteLine($"\n\nFirst positive even value: { firstPosEvenX }.");
// another way to do this: pass a delegate referencing a lambda expression
MyPredicate predicate2 = x => (x) > 0 && x % 2 != 0; // boolean expression for 'positive' 'odd'
int firstPositiveOdd = Find(predicate2);
Console.WriteLine($"\n\nFirst positive odd value (Lambda-style): { firstPositiveOdd }.");
// Create an example using a Delegate that takes two int parameters and returns bool
// then wire-up the Delegate to a method that collects all matching instances of x
// return the count of matches
MyPredicate2 mp2 = AreEqual;
List <int> matches = MyFindAll(mp2);
Console.WriteLine($"\n\nNumber of matching items found: { matches.Count }.");
Console.WriteLine("\n\nPress <Enter> to exit. . .");
Console.ReadLine();
}
public static int CountElements(this int[] arr, MyPredicate predicate)
{
int counter = 0;
foreach (var item in arr)
{
if (predicate(item))
{
counter++;
}
else
{
Console.WriteLine("false number");
}
}
return(counter);
}
static void Main(string[] args)
{
List <string> source = new List <string> {
"Bill", "John", "David", "Tom", "David"
};
MyPredicate predicate = SearchDavid;
MyClass myClass = new MyClass();
Console.Write("Ender :");
string s = Console.ReadLine();
var result = myClass.DoWhere(source, predicate, s);
foreach (var item in result)
{
Console.WriteLine(item);
}
Console.ReadLine();
}
public Form1()
{
InitializeComponent();
//1: Create a delegate object to a named method
//d1 = new MyPredicate(IsEvenPositive);
//Or use a short-cut syntax
d1 = IsEvenPositive;
//2: Create a delegate to an anonymous method
d2 = delegate(int x)
{
return(x > 0 && x % 2 == 0);
};
//3: Create a delegate to a lambda expression
d3 = x => x > 0 && x % 2 == 0;
d4 = (x, y) => x > 0 && x % 2 == 1 && y >= Math.Pow(x, 2);
d5 = (a, b) => (a.Average() + b.Average() / 2);
}
static void Main(string[] args)
{
var words = new List <string>()
{
"1", "12", "123", "1234", "12345", "12346", "1234567"
};
Console.Write("Maximum length of string to include? ");
int userMaxLength = int.Parse(Console.ReadLine()); // userMaxLength scope is in Main
MyPredicate <string> predicate = item => item.Length < userMaxLength; // we create an anonymous method that uses a variable decalred outside of itself
IList <string> shortWords = ListUtil.Filter(words, predicate); // this method is passed to another method
ListUtil.Dump(shortWords); // and userMaxLength int is still available
//Console.WriteLine("Changing the value of the scoped variable within the predicate:");
//userMaxLength = 0;
//MyPredicate<string> predicate2 = item => { userMaxLength++; return item.Length <= userMaxLength; };
//IList<string> shortWords2 = ListUtil.Filter(words, predicate2);
//ListUtil.Dump(shortWords2);
}
static void Main(string[] args)
{
// 建立來源資料
List <string> source = new List <string> {
"Bill", "John", "David", "Tom", "David"
};
MyCalss obj = new MyCalss();
// 傳統的具名寫法
MyPredicate predicate = SearchDavid;
var result = obj.DoWhere(source, SearchDavid);
// 以上兩行行加上 SearchDavid 方法可以用匿名委派的寫法
// 請看 DelegateSample003
foreach (var item in result)
{
Console.WriteLine(item);
}
Console.ReadLine();
}
string MyPreParser(string myCondition)
{
if (myCondition == "")
{
print("MyPreParser: Ошибка! Для подготовки логического условия передана пустая строка.");
return("");
}
// Массив структур для отдельных условий
List <MyPredicate> myPredicates = new List <MyPredicate>();
// Соберем выделенные в [...] единичные условия в массив List
int myStart = 0; // с какого символа начинать поиск
for (int i = 0; i < 100; i++) // на всякий случай число возможных предикатов ограничено
{
// Ищем [
int myOpenBracket = myCondition.IndexOf("[", myStart);
if (myOpenBracket == -1) // Открывающая скобка не найдена
{
break; // Больше нет единичных условий
}
// Ищем ]
int myCloseBracket = myCondition.IndexOf("]", myStart);
if (myCloseBracket == -1) // Закрывающая скобка не найдена
{
print("MyPreParser: Ошибка! При подготовке логического условия обнаружена незакрытая квадратная скобка.");
return("");
}
// Вырежем единичное условие и заполним структуру
MyPredicate myPredicate = new MyPredicate();
myPredicate.PrString = myCondition.Substring(myOpenBracket + 1, myCloseBracket - myOpenBracket - 1);
myPredicate.OpenBr = myOpenBracket;
myPredicate.CloseBr = myCloseBracket;
//print("myStart = " + myStart + " myOpenBracket = " + myOpenBracket + " myCloseBracket = " + myCloseBracket + " mySubStr = " + myPredicate.PrString);
// Добавим структуру в массив
myPredicates.Add(myPredicate);
// Новый старт для поиска
myStart = myCloseBracket + 1;
if (myStart >= myCondition.Length)
{
break; // дошли до конца строки
}
}
// Cтрока для формирования окончательного логического выражения
StringBuilder myCond = new StringBuilder();
// Обработаем каждый предикат
for (int i = 0; i < myPredicates.Count; i++)
{
print(myPredicates[i]);
string[] mySubStr = myPredicates[i].PrString.Split(new char[] { '.', '=' });
string myPath = mySubStr[0];
string propName = mySubStr[1];
string propValue = mySubStr[2];
// Получить Control:
print("myPath = " + myPath);
Control ctrl = _worldController.SourceControls[myPath];
bool result;
// Получить логическое значение предиката
if (ctrl != null)
{
result = ctrl.GetState(propName, propValue);
}
else
{
print("MyPreParser: Не удается получить Control по пути: " + myPath);
result = false;
}
// Собрать строку, заменяя в ней условия [...] на их логические значения
if (i == 0) // могут быть символы до первой открывающейся скобки
{
myCond.Append(myCondition.Substring(0, myPredicates[i].OpenBr));
}
myCond.Append(result);
if (i < myPredicates.Count - 1) // это еще не последний предикат
{
myCond.Append(myCondition.Substring(myPredicates[i].CloseBr + 1, myPredicates[i + 1].OpenBr - myPredicates[i].CloseBr - 1));
}
else // а вот это уже последний
{
myCond.Append(myCondition.Substring(myPredicates[i].CloseBr + 1, myCondition.Length - myPredicates[i].CloseBr - 1));
}
}
print("MyPreParser return " + myCond.ToString());
return(myCond.ToString());
}
