Avoid Mixing LINQ and Traditional Loops

Mixing LINQ and traditional loops can lead to confusing and hard-to-maintain code. Choose one approach and stick with it within a method:

// Avoid mixing like this:
var query = users.Where(u => u.IsActive);
foreach (var user in query)
{
    if (user.Age > 30)
    {
        // Do something
    }
}


// Prefer this:
var relevantUsers = users.Where(u => u.IsActive && u.Age > 30);
foreach (var user in relevantUsers)
{
    // Do something
}