C# Array.Clear Examples

Use the Array.Clear method to zero out all array elements. Measure the performance of Clear.

Array.Clear. This method zeros out elements in a range. It provides a one-line, reliable and understandable way to empty or clear your array.

This method works on arrays of any type—including numbers, booleans, structs and class instances. We can provide a start index, and a length.Array

First example. Many arrays use integers or other value types such as char. In the C# language, these types of arrays are always initialized to 0.Char Array

Program: We use Array.Clear to reset all elements in an int array to zero, without reallocating the array or changing its reference.

Int Array

Length: We use the Length property of the array as the third argument. This clears all elements.

Array Length

C# program that uses Array.Clear using System; class Program { static void Main() { int[] integerArray = new int[] { 4, 6, 8, 1, 3 }; // // Display the array // Console.WriteLine("--- Integer array before ---"); foreach (int value in integerArray) { Console.WriteLine(value); } // // Clear all elements in the array. // Array.Clear(integerArray, 0, integerArray.Length); // // Display the array // Console.WriteLine("--- Integer array after ---"); foreach (int value in integerArray) { Console.WriteLine(value); } } } Output --- Integer array before --- 4 6 8 1 3 --- Integer array after --- 0 0 0 0 0

Example 2. This example shows an array of objects, each with 2 properties. The Array.Clear method is used to set the first 2 references in the array to null.Null

Here: The first argument to Array.Clear is the target array to clear. And the second specifies the offset to start clearing at.

Tip: The third argument uses Math.Min to clear either 2 elements or all elements, whichever is smaller.

Also: If you clear 2 elements and the array has one element, you will get an error. Math.Min prevents this exception.

Math.Max, Min

C# program that clears object array using System; class Program { class Employee { public string Name { get; set; } public int Salary { get; set; } } static void Main() { Employee[] employees = new Employee[3]; employees[0] = new Employee() { Name = "Bob", Salary = 10000 }; employees[1] = new Employee() { Name = "Susan", Salary = 13000 }; employees[2] = new Employee() { Name = "John", Salary = 20000 }; // // Display the employee array. // Console.WriteLine("--- Employee array before ---"); foreach (Employee employee in employees) { Console.Write(employee.Name); Console.Write(": "); Console.WriteLine(employee.Salary); } // // Clear first two elements in employee array. // Array.Clear(employees, 0, Math.Min(2, employees.Length)); // // Display the employee array. // Console.WriteLine("--- Employee array after ---"); foreach (Employee employee in employees) { if (employee != null) { Console.Write(employee.Name); Console.Write(": "); Console.WriteLine(employee.Salary); } else { Console.WriteLine("null"); } } } } Output --- Employee array before --- Bob: 10000 Susan: 13000 John: 20000 --- Employee array after --- null null John: 20000

Performance, Array.Clear. Here we test the performance of the Array.Clear method. Logically, Array.Clear could be implemented with a for-loop.

Version 1: The Array.Clear method is invoked. It clears the 128-element int array that was allocated as a local variable.

Version 2: Here we use a for-loop and assign each element to zero. We time this version and the previous version.

Result: The for-loop version may be faster because we use 0 directly, instead of a "default" value.

C# program that benchmarks Array.Clear using System; using System.Diagnostics; class Program { const int _max = 10000; static void Main() { int[] array = new int[128]; // Version 1: clear with Array.Clear. var s1 = Stopwatch.StartNew(); for (int i = 0; i < _max; i++) { Array.Clear(array, 0, array.Length); } s1.Stop(); // Version 2: clear with for-loop. var s2 = Stopwatch.StartNew(); for (int i = 0; i < _max; i++) { for (int z = 0; z < array.Length; z++) { array[z] = 0; } } s2.Stop(); Console.WriteLine(((double)(s1.Elapsed.TotalMilliseconds * 1000000) / _max).ToString("0.00 ns")); Console.WriteLine(((double)(s2.Elapsed.TotalMilliseconds * 1000000) / _max).ToString("0.00 ns")); } } Output 280.49 ns Array.Clear 45.23 ns for

A discussion. Boolean arrays are cleared by having all their elements assigned to false. Also, struct arrays will be cleared the same way as other arrays of System.ValueType instances.

Note: All struct fields will be set to null or 0, depending on their type. The default value can be found with the default operator.

Struct Default

A summary. Array.Clear is frequently useful in programs. It is a one-line way of resetting your entire array to its default values. It works on arrays of values and references.

The Dev Codes

.Net

.NET Array Dictionary List String 2D Async DataTable Dates DateTime Enum File For Foreach Format IEnumerable If IndexOf Lambda LINQ Parse Path Process Property Regex Replace Sort Split Static StringBuilder Substring Switch Tuple

Java

Core Array ArrayList HashMap String 2D Cast Character Console Deque Duplicates File For Format HashSet If IndexOf Lambda Math ParseInt Process Random Regex Replace Sort Split StringBuilder Substring Switch Vector While

TheDeveloperBlog.com

C# Array.Clear Examples

Related Links:

.Net

Java

Related Links