When traversing collections of data in C#, developers wield a diverse arsenal of tools. Among the most prominent stand Arrays and Lists, powerful contenders often vying for the same role. Yet, beneath their shared purpose lies a nuanced tapestry of advantages and drawbacks, beckoning careful evaluation before making the optimal choice.
Arrays
An Array is a built in type in c#, generally an array is the first way that an aspiring developer is introduced to collections.
The below creates an array of Integers
var array = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
Advantages
- Arrays in c# are strongly typed and as such they will have better performance as boxing/unboxing will not occur.
- Arrays will consume less memory.
- As arrays are strongly typed any type mismatches will be caught at compile time.
Disadvantages
- Arrays require a size set on initilisation and this cannot be changed.
- Items are stored consecutively in memory it is costly to insert or delete an item in an array.
For more information on Arrays in c# Click Here
Lists
A List is a generic collection in c# that represents a strongly typed list of objects that can be accessed by index.
The below creates an List of Integers
var list = new List<int> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
Advantages
- Lists provide methods to search, sort and manipulate (Add / Remove items).
- The size does not need to be determined at initilisation.
Disadvantages
- Lists are more costly Initialise compared to arrays.
- Lists consume more memory compared to arrays.
- As Lists are generic this allows for type mismatch runtime errors.
For more information on the List generic class in c# Click Here
Benchmark
All following tests the creation of Arrays or Lists of identical objects
- A set of 11 and a set of 101 Integers
- A set of 11 and a set of 101 Strings
- A set of 11 and a set of 101 Classes
- A set of 11 Records
| Test | Mean | Error | StdDev | Gen0 | Gen1 | Allocated |
|---------------- |-----------:|------------:|----------:|-------:|-------:|----------:|
| IntegerArray11 | 3.153 ns | 0.4993 ns | 0.0274 ns | 0.0046 | - | 72 B |
| IntegerList11 | 27.487 ns | 3.8722 ns | 0.2123 ns | 0.0138 | - | 216 B |
| IntegerArray101 | 13.875 ns | 13.2419 ns | 0.7258 ns | 0.0250 | - | 392 B |
| IntegerList101 | 117.153 ns | 54.3591 ns | 2.9796 ns | 0.0755 | 0.0001 | 1184 B |
| StringrArray11 | 4.410 ns | 1.0272 ns | 0.0563 ns | 0.0071 | - | 112 B |
| StringList11 | 41.022 ns | 9.3459 ns | 0.5123 ns | 0.0209 | - | 328 B |
| StringrArray101 | 33.412 ns | 10.9841 ns | 0.6021 ns | 0.0530 | - | 832 B |
| StringList101 | 166.764 ns | 37.4811 ns | 2.0545 ns | 0.1397 | 0.0007 | 2192 B |
| ClassArray11 | 41.823 ns | 9.1801 ns | 0.5032 ns | 0.0352 | 0.0001 | 552 B |
| ClassList11 | 84.088 ns | 28.9425 ns | 1.5864 ns | 0.0489 | - | 768 B |
| ClassArray101 | 373.902 ns | 41.7738 ns | 2.2898 ns | 0.3104 | 0.0052 | 4872 B |
| ClassList101 | 601.145 ns | 161.2419 ns | 8.8382 ns | 0.3967 | 0.0076 | 6232 B |
| RecordArray | 42.003 ns | 9.5369 ns | 0.5228 ns | 0.0352 | 0.0001 | 552 B |
| RecordList | 89.668 ns | 64.3446 ns | 3.5269 ns | 0.0489 | - | 768 B |
In all tests the time that was required to construct an array as well as the amount of memory used was significantly less compared to using a List. The above shows that on average it took nine times longer to construct a List of integers and consumed three times the memory compared to an Array.
Conclusion
Arrays and Lists both have their uses in c#, if the intent is to store a set of data that will not change (i.e. a list of currencies that your app supports) then an Array is the better option, however if you require dynamism in your set then a List is better suited.