关于 UE4 TMap 的几种遍历方式
测试数据
1 TMap<int32, FString> Map1; 2 TMap<int32, FString> Map2; 3 4 Map1.Add(1, TEXT("AAA")); 5 6 ShowMap_1(Map1, 1); 7 ShowMap_2(Map1, 1); 8 ShowMap_3(Map1, 1);
1. 通过 Key 直接查找 Map
1 // 通过 Key 直接查找 Map 2 auto ShowMap_1 = [](const TMap<int32, FString> Value, int32 Key)->void 3 { 4 if (Value.Contains(Key)) 5 { 6 UE_LOG(LogTemp, Display, TEXT("Key is %d value is: %s"), Key, *Value[Key]); 7 } 8 else 9 { 10 UE_LOG(LogTemp, Display, TEXT("Key %d is error"), Key); 11 } 12 };
1 // 调用 2 ShowMap_1(Map1, 1); 3 ShowMap_1(Map1, 2);
2. 通过 Find 查找 Map
1 auto ShowMap_2 = [](const TMap<int32, FString> Value, int32 Key)->void 2 { 3 if (Value.Contains(Key)) 4 { 5 const FString* Vall = Value.Find(Key); 6 if (Vall != nullptr) 7 { 8 UE_LOG(LogTemp, Display, TEXT("Key is %d value is: %s"), Key, Vall->operator*()); 9 } 10 else 11 { 12 UE_LOG(LogTemp, Display, TEXT("Key %d Ptr error"), Key); 13 } 14 } 15 else 16 { 17 UE_LOG(LogTemp, Display, TEXT("Key %d is error"), Key); 18 } 19 };
1 // 调用 2 ShowMap_2(Map1, 1); 3 ShowMap_2(Map1, 2);
3. 通过 FindRef 查找 Map
1 auto ShowMap_3 = [](const TMap<int32, FString> Value, int32 Key)->void 2 { 3 if (Value.Contains(Key)) 4 { 5 const FString Vall = Value.FindRef(Key); 6 if (&Vall != nullptr) 7 { 8 // UE_LOG(LogTemp, Display, TEXT("Key is %d value is: %s"), Key, *Vall); 两种方式都可以 9 UE_LOG(LogTemp, Display, TEXT("Key is %d value is: %s"), Key, Vall.operator*()); 10 } 11 else 12 { 13 UE_LOG(LogTemp, Display, TEXT("Key %d Ptr error"), Key); 14 } 15 } 16 else 17 { 18 UE_LOG(LogTemp, Display, TEXT("Key %d is error"), Key); 19 } 20 };
1 // 调用 2 ShowMap_3(Map1, 1); 3 ShowMap_3(Map1, 2);
