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C# bool Array (Memory Usage, One Byte Per Element)Allocate an array of bools, measuring the memory usage of bool elements.
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Bool array. In C# a program, a bool array requires one byte per element. It can store many true and false values, and are easy to use.
Array benefits. Boolean arrays are simple and allow for safe and clear code. They are not optimally memory-efficient, but often they are good enough.
Bool
Array
An example. To start, we allocate and initialize bool arrays. The syntax is the same as other arrays, in that you need to specify the array length inside the square brackets.
Tip When you allocate the bool array, its values are filled with False. You do not need to initialize any values to False in your code.
Info You should initialize values to True as required. You can loop over bool arrays with foreach or with for.
Foreach
For
C# program that uses bool array
using System; class Program { static void Main() { // // Initialize new bool array. // bool[] array = new bool[10]; array[0] = false; // <-- Not needed array[1] = true; array[2] = false; // <-- Not needed array[3] = true; // // Loop through all values. // foreach (bool value in array) { Console.WriteLine(value); } } }
False True False True False False False False False False
Memory. The bool value can be expressed with a single bit in memory—one means true and zero means false. However, the bool type in C# is expressed in eight bits, or one byte.
Info We look at a program that allocates one million bools. This results in 1,000,012 bytes being allocated.
However One million bits is only 125,000 bytes. So a bool array representation is less efficient.
C# program that allocates bool array
using System; class Program { static void Main() { // // Initialize new bool array. // bool[] array = new bool[1000000]; // // Initialize each other value to true. // for (int i = 0; i < array.Length; i += 2) { array[i] = true; } } }
Size of the array in memory: 1,000,012 bytes [CLRProfiler]. Each bool requires 1 byte. Array reference requires 12 bytes.
Sort. Sorting bool arrays is useful for certain algorithms. It can help methods that favor some object, but do not want to remove objects.
bool Sort
Arguments. As with other arrays, you can pass bool arrays as arguments by using the bool[] type for the parameter. You can also return bool arrays from methods with the same type.
Tip Due to the extra address space required for booleans, it is better to use BitArray when you have trillions of values.
BitArray. There is a BitArray class in the System.Collections namespace. This is more compact than bool arrays, and can reduce memory usage.
BitArray
Summary. The program showed that elements in bool arrays are initialized to false automatically. We saw that bool arrays require one byte for each element.
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