Given List<object> mixed = new() { 5, "text", 7, 3.14, 10 };, which code snippet correctly creates a list of only the integers using pattern matching?
hard🚀 Application Q8 of Q15
C Sharp (C#) - Polymorphism and Abstract Classes
Given List<object> mixed = new() { 5, "text", 7, 3.14, 10 };, which code snippet correctly creates a list of only the integers using pattern matching?
Avar ints = mixed.Where(item => item is int i).Select(item => (int)item).ToList();
Bvar ints = mixed.Where(item => item is int i).Select(i => i).ToList();
Cvar ints = mixed.OfType<int>().ToList();
Dvar ints = mixed.Select(item => item as int).ToList();
Step-by-Step Solution
Solution:
Step 1: Understand the goal
We want a list containing only the integers from the mixed list.
Step 2: Analyze options
var ints = mixed.Where(item => item is int i).Select(item => (int)item).ToList(); uses pattern matching but incorrectly selects (int)item without using the matched variable. var ints = mixed.OfType().ToList(); uses OfType<int>() which filters and casts correctly. var ints = mixed.Where(item => item is int i).Select(i => i).ToList(); tries to select i but i is not in scope in the lambda. var ints = mixed.Select(item => item as int).ToList(); uses as int which is invalid because int is a value type.
Final Answer:
var ints = mixed.OfType<int>().ToList(); -> Option C
Quick Check:
Use OfType<T>() to filter and cast [OK]
Quick Trick:OfType() filters and casts in one step [OK]
Common Mistakes:
MISTAKES
Using 'as' with value types
Incorrectly using pattern variable in LINQ
Casting without filtering causing exceptions
Master "Polymorphism and Abstract Classes" in C Sharp (C#)
9 interactive learning modes - each teaches the same concept differently
