乙個從委託應用到LINQ演變的示例

一，乙個賽車手的類表述了賽車手的姓名，國籍，獲獎情況等資訊

[serializable]

public
class racer : icomparable, iformattable
public
string lastname 
public
int wins 
public
string country 
public
int starts 
public
string cars 
public
int years 
public
override
string tostring()
", firstname, lastname);
}public
string tostring(string format)
public
string tostring(string format, iformatprovider formatprovider)
, ; starts: , wins: ",
firstname, lastname, country, starts, wins);
default:
throw
new formatexception(string.format(
"format  not supported", format));}}
public
int compareto(racer other)
}

二，生成賽車手list的類，提供乙個方法生成list

public

class formula1
, cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
racers.add(new racer() , cars = new
string  });
return racers;
}}

三，示例**

static

class  program
", r);
r.putinfo(datetime.now);
}//使用匿名委委託

racers = new list(formula1.getchampions());

brazilracers = racers.findall(
delegate(racer r)
);brazilracers.sort(
delegate(racer r1, racer r2)
);foreach (racer r in brazilracers)
", r);
r.putinfo(datetime.now);
}//使用linq類提供的擴充套件方法
racers = new list(formula1.getchampions());
brazilracers.where(
delegate(racer r)
);brazilracers.orderbydescending(
delegate(racer r)
);brazilracers.select(
delegate(racer r)
);foreach (racer r in brazilracers)
", r);
r.putinfo(datetime.now);
}//運用lamda表括達式
racers = new list(formula1.getchampions());
racers.where(r => r.country == "brazil");
racers.orderbydescending(r => r.wins);
racers.select(r => r);
foreach (racer r in brazilracers)
", r);
r.putinfo(datetime.now);
}//最終演變為linq查詢
racers = new list(formula1.getchampions());
var query = from r in racers
where r.country == "brazil"
orderby r.wins descending
select r;
foreach (racer r in query)
", r);
r.putinfo(datetime.now);
}console.read();
}/// 
/// 擴充套件方法例項
/// 呼叫擴充套件方法只是呼叫靜態方法的一種新語法
/// 
/// 
public
static
void putinfo(this racer r, datetime dt)
", dt.tolongtimestring());
}/// 
/// 用於查詢
/// 
public
static predicate isbrazilhandle = isbrazil;
public
static
bool isbrazil(racer r)
else
}/// 
/// 用於排序
/// 
public
static comparison sortracershandle = new comparison(sortracers);
public
static
int sortracers(racer r1, racer r2)
}

說明：該示例參照c#高階程式設計中關於linq的講解

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