Linq Where query without lambda

Lambda is a useful thing but also a bit confusing for me. can someone please do the linq'WHERE' query without lambda so i can understand whats been happening.

List<Student> st = new List<Student>() {
              new Student(){Id=1,Name="Nav"},
              new Student(){Id=2,Name="San"},
              new Student(){Id=3,Name="Jat"},
        };
                Student? me = st.Where(st => st.Name == "Nav").FirstOrDefault();

I wanna see how to do this without lambda.

First of all, lambdas are a very powerful and common tool in .net and LINQ in particular, so it is very useful to learn how to read and understand them. Lambda expressions in C# allow you to write concise and expressive code that can make your code more readable and easier to understand.

In your code, we use the Where method of the List<T> class along with a lambda expression to filter the list of students and get the student whose Name property matches "Nav".

here's an example of how to achieve the same result without using lambda expressions and LINQ at all:

var st = new List<Student>() {
   new Student(){ Id = 1, Name = "Nav" },
   new Student(){ Id = 2, Name = "San" },
   new Student(){ Id = 3, Name = "Jat" },
};

Student firstOrDefaultStudent = null;

foreach (Student s in st)
{
    // if is analog for where
    // we compare the Name property of each student with the string "Nav". 
    // When we find a student whose Name property matches "Nav", 
    // we assign that student to the variable "firstOrDefaultStudent"
    if (s.Name == "Nav")
    {
        firstOrDefaultStudent = s;
        // this is analog for first or default
        // when we find first matched value we stop our loop 
        // because we need only first student that matches condition
        break;
    }
}

Also you can replace your lambda with method. This method will be called for each item in the collection and return a bool value, which means whether the item fits the condition described in the method or not.

var st = new List<Student>() {
   new Student(){ Id = 1, Name = "Nav" },
   new Student(){ Id = 2, Name = "San" },
   new Student(){ Id = 3, Name = "Jat" },
};

Student? me = st.Where(IsNameEqualsToNav).FirstOrDefault();

private static bool IsNameEqualsToNav(Student st)
{
    return st.Name == "Nav";
}

Please remember about another important LINQ behavior. LINQ operations are often implemented to use deferred execution:

> Deferred execution means that the evaluation of an expression is delayed until its realized value is actually required. Deferred execution can greatly improve performance when you have to manipulate large data collections, especially in programs that contain a series of chained queries or manipulations. In the best case, deferred execution enables only a single iteration through the source collection.

> The LINQ technologies make extensive use of deferred execution in both the members of core System.Linq classes and in the extension methods in the various LINQ namespaces, such as System.Xml.Linq.Extensions.