Extension Method for List to compute WhereNot-CodePudding

I have one requirement to implement the extension method for List to find out the WhereNot. I am not suppose to use any existing Linq extension method like where etc.

For Example

IEnumerable<int> list = new List<int> {1,2,3,4,5,6};
var whereNotListInt = list.WhereNot((num) => num > 3));

foreach(int i in whereNotListInt)
{
   Console.WriteLine(i);
}

Output:- 1 2 3

IEnumerable<string> list = new List<string> {"Cat", "Dog"};
var whereNotListStr = list.WhereNot((str) => str.StartsWith("D")));

foreach(string str in whereNotListStr )
{
   Console.WriteLine(str);
}

Output: Cat

I tried below solution, but not able to figure out how to call the function.

public static class Utility
    {
        public static IEnumerable<T> WhereNot<T>(this IEnumerable<T> list, Func<T, bool> func)
        {
            foreach (var item in list)
            {
                yield return func(item);
            }    
        }
    }

CodePudding user response：

Since you only want to return items for which the condition is not true, only return each item when func() returns false on that item.

public static class Utility
{
    public static IEnumerable<T> WhereNot<T>(this IEnumerable<T> list, Func<T, bool> func)
    {
        foreach (var item in list)
        {
            if (!func(item))
                yield return item;
        }    
    }
}