UE官方文档学习 C++ TAarry 查询（三）Contain，Find函数的使用

一.Contain

Contain只是判断是否有这个元素.

但ContainsByPredicate ，通过重新定义谓词 == 。不仅能判断，是否有符合这个元素的长度元素（谓词）。还能断言打日志。这里就使用Lamda函数值传递，一直对每个下标累加，标记。从头开始找，直到找到满足条件的就返回，为true。找不到就为false

void AWXArrayActor::WXContainArray()
{TArray<FString> StrArr = { "1234756","33","Hello", "World", "of", "Tomorrow","!" };bool bHello = StrArr.Contains("Hello");bool bFuck = StrArr.Contains("Fuck");int32 bFind5Character = 0;//bool bLen5 = StrArr.ContainsByPredicate([&bFind5Character](const FString& Str) {++bFind5Character;UE_LOG(LogTemp,Warning,TEXT("bLen5,[%d]"), bFind5Character);return Str.Len() == 5;});int32 bFind6Character = 0;bool bLen6 = StrArr.ContainsByPredicate([&bFind6Character](const FString& Str) {++bFind6Character;UE_LOG(LogTemp,Warning,TEXT("bLen6,[%d]"),bFind6Character);return Str.Len() == 6;});// bLen5 == true// bLen6 == false}

二、Find来找

可以从前面找或者后面找，返回下标。找到第一个，最好默认为-1。

void AWXArrayActor::XGFindElementArray()
{TArray<FString> StrArr = { "Hello", "World", "of", "Tomorrow","Hello","!" };int32 Index = -1;if (StrArr.Find(TEXT("Hello"), Index)){}bool bIndex = StrArr.Find(TEXT("Hello"), Index);int32 LastIndex = -1;if (StrArr.FindLast(TEXT("Hello"), LastIndex)){}bool bIndexFromLast = StrArr.FindLast(TEXT("Hello"), LastIndex);int32 ErrorIndex = -1;bool bErrorIndex = StrArr.FindLast(TEXT("Fuck"), ErrorIndex);int32 Index2 = StrArr.Find(TEXT("Hello"));int32 IndexLast2 = StrArr.FindLast(TEXT("Hello"));int32 IndexNone = StrArr.Find(TEXT("None"));bool bIndexNone = INDEX_NONE == IndexNone;
}