摘選自c#高階程式設計(第9版) --c# 5.0 & .net 4.5.1
code:
static void main(string args)
;var q = data.oftype();//oftype使用
//多個from,實際是轉為selectmany()擴充套件方法
var ferraidrivers = from r in formula1.getchampions()
from c in r.cars
where c == "ferrari"
orderby r.lastname
select r.firstname + " " + r.lastname;
//對應擴充套件方法為
var ferraidrivers2 = formula1.getchampions()
.selectmany(r => r.cars, (r, c) => new )
.where(r => r.car == "ferrari")
.orderby(r => r.racer.lastname).select(r => r.racer.firstname + " " + r.racer.lastname);
foreach (var s in ferraidrivers)
console.writeline(s);
//join
var racersandteams = (from r in
from r1 in formula1.getchampions()
from yr in r1.years
select new
join t in
from t1 in formula1.getcontructorchampions()
from yt in t1.years
select new
on r.year equals t.year
orderby t.year
select new
).take(10);
foreach (var item in racersandteams)
: ", item.year, item.racer, item.team);
}//intersect操作
func> racersbycar =
car => from r in formula1.getchampions()
from c in r.cars
where c == car
orderby r.lastname
select r;
console.writeline("world champion with ferrari and mclaren");
foreach (var racer in racersbycar("ferrari").intersect(racersbycar("mclaren")))
//zip(合併)
console.writeline("zip:");
var racernames = from r in formula1.getchampions()
where r.country == "itally"
orderby r.wins descending
select new
;var racernamesandstarts = from r in formula1.getchampions()
where r.country == "itally"
orderby r.wins descending
select new
;var racers = racernames.zip(racernamesandstarts, (a, b) => a.name + ",starts:" + b.starts);
foreach (var r in racers)
console.writeline(r);
//count sum
var query = from r in formula1.getchampions()
let nyears = r.years.count()
where nyears >= 3
orderby nyears descending, r.lastname
select new
;foreach (var r in query)
console.writeline(" ", r.name, r.timeschampion);
var countries = (from c in
from r in formula1.getchampions()
group r by r.country into c
select new
orderby c.wins descending, c.country
select c).take(5);
foreach (var c in countries)
console.writeline(" ", c.country, c.wins);
//非型別化的集合操作
var l = new arraylist(formula1.getchampions() as icollection);
var query1 = from r in l.cast()
where r.country == "usa"
orderby r.wins descending
select r;
foreach (var r in query1)
console.writeline("", r);
console.readkey();
}
private static void linqquery()
", r);
}}
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