Cast() vs. OfType() in LINQ: When Should I Use Each?

Choosing Between Cast() and OfType() in Linq

In the realm of LINQ, casting types from an ArrayList to an IEnumerable can be accomplished with two methods: Cast() and OfType(). Understanding their nuances is crucial for selecting the appropriate approach for different scenarios.

Cast() attempts to cast every element in the ArrayList as if it were of the specified type. Any elements that cannot be successfully cast will result in an InvalidCastException exception being thrown.

OfType(), on the other hand, only returns elements that can be safely cast to the specified type. It skips any elements that cannot be cast, effectively filtering the ArrayList to only include elements of the desired type.

When to Use Each Method

• Use Cast() when: You want to enforce a specific type on all elements in the ArrayList, even if it means excluding elements that cannot be cast.
• Use OfType() when: You want to preserve the original ArrayList and only work with elements that can be safely cast to the specified type.

Illustrative Example

Consider the following ArrayList:

object[] objs = new object[] { "12345", 12 };

• objs.Cast().ToArray(); will throw an InvalidCastException because the second element cannot be cast to a string.
• objs.OfType().ToArray(); will return { "12345" }, as only the first element can be cast to a string.

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