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涓€锛氳儗鏅?/span>
1. 璁叉晠浜?span class="mq-7">
鏈€杩戝彂鐜?C#7 涔嬪悗鐨?is 鏄秺鏉ヨ秺鐪嬩笉鎳備簡锛屼箥涓€鐪嬭姳閲岃儭鍝ㄧ殑锛屼笉杩囧綋鎴戦潤涓嬪績鏉ヤ粩缁嗙爺璇伙紝鍙戠幇杩?is 鏄秺鏉ヨ秺鐭皬绮炬倣锛岃€屼笖杩樼壒鍒涔夊寲锛岄偅鎬庢槸涓€涓埥瀛椾簡寰楌煒勶紝杩欎竴绡囧氨鍜屽ぇ瀹剁畝鍗曡亰涓€鑱娿€?/p>
浜岋細C#7 涔嬪墠鐨?is 濡備綍浣跨敤
1. 绫诲瀷鍏煎鎬ф娴?span class="mq-15">
鐩镐俊瀛﹁繃 C# 鐨勬湅鍙嬮兘浼氱煡閬?is 鏄共鍢涚殑锛岃€屼笖杩樼粡甯稿拰 as 涓€璧锋瘮杈冿紝鍓嶈€呬竴鑸仛鍏煎鎬ф娴嬶紝鍚庤€呬竴鑸仛鍏煎鎬ц浆鎹紝杩欓噷鎴戝氨涓句釜渚嬪瓙鍚э細
static void Main(string[] args)
{
object slot = new Slot() { ClothesName = "涓婅。" };
if (slot is Slot)
{
Console.WriteLine($"slot is {nameof(Slot)}");
}
if (slot is IComparable)
{
Console.WriteLine($"slot is {nameof(IComparable)}");
}
}
public class Slot : IComparable
{
public string ClothesName { get; set; }
public int CompareTo(object obj) {return 0;}
}
浠庤繖涓緥瀛愬彲浠ョ湅鍒帮紝 object 绫诲瀷鐨?slot 鍜?Slot, IComparable 閮芥槸绫诲瀷鍏煎鐨勶紝闈炲父绠€鍗曘€?/p>
2. 閬楁喚鐨勫湴鏂?span class="mq-58">
鐒惰€屽湪瀹為檯缂栫爜涓紝鎴戠浉淇℃湁寰堝鏈嬪弸閮戒細鍦ㄥ悗缁殑杩囩▼涓敤鍒?slot 瀹炰緥锛岃€屼笂闈㈢殑杩欎釜渚嬪瓙锛屽嵆浣挎垜鐢?is 妫€娴嬪埌浜嗘槸 Slot 绫诲瀷锛屾渶鍚庢垜杩樻槸瑕?灏?object slot 寮鸿浆鎴?Slot绫诲瀷锛屽仛浜嗕竴娆℃娴嬶紝鍙堝仛浜嗕竴涓己杞紝杩欏氨寰堝钁╀簡锛屽涓嬩唬鐮侊細
if (slot is Slot)
{
var query = (Slot)slot;
Console.WriteLine($"slot is {nameof(Slot)}, ClothesName={query.ClothesName}");
}
闄ら潪鏈夋瘺鐥呮墠鍐欒繖鏍风殑浠ｇ爜锛屽共鍢涗笉鐩存帴鐢?as 灏濊瘯鎬ц浆鎹㈠皢涓ゆ鍚堜负涓€姝ヨ蛋鍛紵淇敼浠ｇ爜濡備笅锛?/p>
var query = slot as Slot;
if (query != null)
{
Console.WriteLine($"slot is {nameof(Slot)}, ClothesName={query.ClothesName}");
}
杩欏氨瀵艰嚧寰堝鍦烘櫙涓嬶紝is 閮借 as 鏇夸唬浜嗭紝鎼炵殑 is 鎴愪簡涓€涓┖鏋跺瓙锛屽鏋?is 鑳藉悎骞?as 鐨勫姛鑳斤紝閭ｅ氨馃悅馃憙浜嗭紝鎴戣寰楄繖涓€ラ渶澧炲己銆?/p>
涓夛細C#7 涔嬪悗鐨?is 濡備綍浣跨敤
涔熺粓浜庡湪 C#7 涔嬪悗瀵?is 杩涜浜嗙炕澶╄鍦扮殑璇硶绯栨敼閫狅紝瀵艰嚧浣犲垵鐪嬪凡缁忎笉鏄庣櫧鍟︷煒勷煒勷煒勶紝涓嬮潰鎴戝氨涓€涓€涓句緥鏉ヨ鏄庡惂銆?/p>
1. is 鍜?澶嶆潅绫诲瀷/绠€鍗曠被鍨?鐨勭粨鍚?span class="mq-90">
鐜板湪灏辨潵鐪嬩竴涓嬫€庝箞鐢ㄦ柊is 瑙ｅ喅鍒氭墠涓ゆ杞崲鐨勯棶棰橈紝濡備笅浠ｇ爜锛?/p>
object slot = new Slot() { ClothesName = "涓婅。" };
if(slot is Slot query)
{
Console.WriteLine($"slot is {nameof(Slot)}, ClothesName={query.ClothesName}");
}
杩欐浠ｇ爜琛ㄩ潰鎰忔€濇槸锛氬厛鐢?is 妫€娴?slot 鏄惁涓?Slot 绫诲瀷锛屽鏋滄槸灏辫祴鍊肩粰 Slot 绫诲瀷鐨?query 鍙橀噺锛屽搱鍝堬紝鏈夌偣鎰忔€濆惂锛屼负浜嗛獙璇佹槸鍚﹀鎴戞墍璇达紝鐢ㄥ弽缂栬瘧宸ュ叿鐪嬬湅銆?/p>
-
ILSpy 鍙嶇紪璇?
鍙互鐪嬪埌锛屽湪瀹炴搷涓紝缂栬瘧鍣ㄩ兘鐢?as 杩涜浜嗚繕鍘燂紝涓嶈繃浠庝唬鐮佹祦鐣呮€ф潵鐪嬶紝ILSpy鏇答煇傪煈冧竴鐐广€?/p>
闄や簡鍜岀被瀹炰緥姣旇緝涔嬪锛岃繕鍙互鍜?int,string,tuple ...杩涜姣旇緝锛?浠ｇ爜濡備笅锛?/p>
object e = 150;
//瀛楃涓叉瘮杈?/span>
if (e is "hello") { }
//鏁村舰姣旇緝
if (e is 10) { }
//tuple 姣旇緝
if (e is (10, 20)) { }
2. is 鍜?null 鐨勭粨鍚?span class="mq-137">
澶у鍦ㄥ啓 sql 鐨勬椂鍊欏垽鏂煇涓€涓瓧娈垫槸鍚︿负 null锛岄€氬父閮戒細杩欐牱鍐欙細username is null 鎴栬€?username is not null 锛屽搱鍝堬紝杩欑鍐欐硶涔熻寮曞叆鍒?C# 涓簡锛屾湁鎰忔€濆惂锛屼笂浠ｇ爜锛?/p>
object e = 150;
if (e is null)
{
Console.WriteLine("e is null");
}
if (e is not null)
{
Console.WriteLine("e is not null");
}
杩欎箞璇箟鍖栫殑鍐欐硶鍦–#涓湅鍒版槸涓嶆槸鏈夌偣涓嶄範鎯紝閭ｄ负鍟ュ湪 sql 涓氨涔犱互涓哄父鍛紵鍏跺疄鍙嶇紪璇戣繃鏉ヤ篃娌″暐锛屽氨鏄竴涓?== 鍒ゆ柇锛屽涓嬩唬鐮侊細
3. is 鍜?and 锛宱r 鐨勭粨鍚?span class="mq-158">
鐜板湪澶у閮界湅鍒颁簡 is 閫氬父鏄斁鍦?if 璇彞涓紝鏃㈢劧鍦?if 璇彞涓紝閭ｈ偗瀹氭湁寰堝鐨勯€昏緫鍒ゆ柇锛岃繖灏遍渶瑕佺粨鍚?and锛宱r 鏋勫缓闈炲父澶嶆潅鐨勯€昏緫鍏崇郴锛屼笉瑕佺溂鑺卞摝銆?/p>
object e = 150;
if (e is >= 100 and <= 200)
{
Console.WriteLine($"e={e} 鏋滅劧 澶т簬 100 骞朵笖 灏忎簬 200");
}
if (e is 100 or 150 or 200)
{
Console.WriteLine($"e={e} 鏄湪 100,150,200 涓変釜鏁板瓧涓?);
}
if (e is not null and not "")
{
Console.WriteLine($"e={e}锛屾ā鎷?nbsp;!string.IsNullOrEmpty 鍔熻兘");
}
鍙互鐪嬪埌鏈€鍚庣殑: e is not null and not "" 鍏跺疄绛変环浜?!string.IsNullOrEmpty, 鏄笉鏄湁鐐规剰鎬濆搱銆?/p>
杩欓噷鏈変竴鐐硅鎻愰啋鐨勬槸锛屼笂闈㈢殑 e 鍦ㄧ紪璇戝櫒灞傞潰閮芥槸 object 绫诲瀷锛屽鏋滀綘鎯冲湪 缂栬瘧鍣ㄥ眰闈娇鐢?int 杩愪綔锛岃繕鏄敤 渚嬪瓙1 鐨勬柟寮忚浆鎹竴涓嬪搱锛屽涓嬪浘鎵€绀猴細
4. is 鍜?var 鐨勭粨鍚?span class="mq-192">
褰?is 鍜?var 缁撳悎璧锋潵灏辨洿馃悅馃憙浜嗭紝鍙互瀹炵幇鍦?if 鍒ゆ柇鐨勮繃绋嬩腑鐢熸垚涓存椂鍙橀噺锛屽涓嬩唬鐮侊細
int e = 150;
if (e is var i && i >= 100 && i <= 200)
{
Console.WriteLine($"e={i} 鏋滅劧 澶т簬 100 骞朵笖 灏忎簬 200");
}
涓婇潰浠ｇ爜涓殑 i 灏辨槸涓€涓复鏃跺彉閲忥紝鍚庨潰鍋氱殑涓€鍒囦笟鍔￠€昏緫閮芥槸鍩轰簬 i 杩欎釜涓存椂鍙橀噺鐨勶紝濡傛灉杩樻病鏈夐浼氬埌绮剧补锛屾病鍏崇郴锛屾垜涓句竴涓」鐩腑鐨勪緥瀛愬惂銆傘€傘€?/p>
鎴戜滑鍏徃鏄悶琛ｇ墿娲楁钉鑷姩鍖栵紝涔熼渶瑕佸绾夸笅 浼犺緭绾夸笂鐨勮。鏈嶈繘琛岃嚜鍔ㄥ寲涓婃寕锛屽彇璧板拰琛ｇ墿缁勫悎鎼厤锛屼妇涓緥瀛愶細 閲嶇偣鍦ㄤ簬涓婇潰浠ｇ爜鐨? 鎴戣寰?is 鐨勫姛鑳藉寮烘棭灏辫鍑虹幇浜嗭紝鐜板湪缁堜簬鎼炲畾浜嗭紝瓒婃潵瓒婁汉鎬у寲锛岄敭鐩樻暡鍑绘鏁拌秺鏉ヨ秺灏戯紝澶村彂涔熶笉钀戒簡锛岀敋鑷冲張寮€濮嬬浜屾槬浜嗭紝鎬荤殑鏉ヨ杩樻槸閭ｅ彞璇濓紝C# 澶ф硶馃悅馃憙銆?/p>
鎵惧埌 鍒氬ソ鎸備簡涓€浠惰￥瀛怢 && 涓€浠朵笂琛 && 鎬昏。鏈嶄釜鏁?2 鐨?鎸傚瓟鍙?/code>锛岃鏄繕娌″惉鎳傚氨绠椾簡锛岀洿鎺ヤ笂浠ｇ爜璇磋瘽銆?/p>
class Program
{
static void Main(string[] args)
{
var slotList = new List<Slot>()
{
new Slot() {SlotID=1, ClothesID=10,ClothesName="涓婅。", SizeName= "L" },
new Slot() {SlotID=1, ClothesID=20,ClothesName="瑁ゅ瓙", SizeName= "M" },
new Slot() {SlotID=1, ClothesID=11,ClothesName="鐨甫", SizeName= "X" },
new Slot() {SlotID=2, ClothesID=30,ClothesName="涓婅。", SizeName= "L" },
new Slot() {SlotID=2, ClothesID=40,ClothesName="瑁ゅ瓙", SizeName= "L" }
};
//鎵惧埌 鍒氬ソ鎸備簡涓€浠惰￥瀛怢 & 涓€浠朵笂琛 & 鎬昏。鏈嶄釜鏁?2 鐨?nbsp;鎸傚瓟鍙?/span>
var query = slotList.GroupBy(m => m.SlotID).Where(m =>
m.Where(n => n.SizeName == "L").ToList() is var clothesList &&
clothesList.Count(k => k.ClothesName == "瑁ゅ瓙") is 1 &&
clothesList.Count(k => k.ClothesName == "涓婅。") is 1 &&
m.Key == 2
)
.ToDictionary(k => k.Key, v => v.ToList());
}
public class Slot
{
public int SlotID { get; set; }
public int ClothesID { get; set; }
public string ClothesName { get; set; }
public string SizeName { get; set; }
}
}m.Where(n => n.SizeName == "L").ToList() is var clothesList锛岃繖閲岀殑 clothesList 灏辨槸涓存椂鍙橀噺锛屽畠瀛樻斁浜嗘墍鏈?灏哄L 鐨勮。鐗?鍚庣画鐨勬绱㈤兘鏄熀浜庤繖涓?clothesList锛屾槸涓嶆槸澶уぇ鎻愰珮浜嗘绱㈤€熷害~~~鍥涳細鎬荤粨
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