Create c++11_cast.md

Author: cherishman2005

c++11_cast.md

@@ -0,0 +1,17 @@
+# c++11 cast
+
+## static_cast
+
+enum与int型转换
+
+```
+enum class ETileType : uint8
+{
+ENone, ESurface, ESubsurface, EPlatform, EHole, EEnd
+};
+```
+
+```
+uint8 n = FMath::RandRange(static_cast<int>(ETileType::ESurface), static_cast<int>(ETileType::EEnd) - 1);
+ETileType NewTile = static_cast<ETileType>(n);
+```