A Pure Implementation Of Push And Pop for a String[] Array not using Queue or Stack

Here's a pure implementation of push and pop functionality of  string[] array in C Sharp, with timings. 

It does not use Queue<T> or Stack; 

For reference, Microsoft's own C# Stack implementation copies to an array! 

1 2 3 4 5 6 7 8 9 10 11 12

// Pushes an item to the top of the stack. // /// <include file='doc\Stack.uex' path='docs/doc[@for="Stack.Push"]/*' /> public void Push(T item) { if (_size == _array.Length) { T[] newArray = new T[(_array.Length == 0) ? _defaultCapacity : 2*_array.Length]; Array.Copy(_array, 0, newArray, 0, _size); _array = newArray; } _array[_size++] = item; _version++; }

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164

using System; namespace FixedLengthStackImplementationofStackofStringsArray { internal class Stack { static readonly int MAX = 3; //Max number of elements in string[] array int count; string[] stack = new string[MAX]; public Stack() //constructor { count = 1; //initialize stack with how many default values stack = new string[] { "x", "y", "z", "w" }; //w is ignored, no error given } public bool IsEmpty() { return (count == 0); } public bool IsFull() { return (count == MAX); } public int Length() { return MAX; } public int Count() { return count; } internal void Push(string data) { if (count > 0) { for (int i = 0; i <= MAX - 2; i++) //inline copy fast stack[i] = stack[i + 1]; stack[MAX - 1] = data; //always same place at top, which in this case is last element of array! if (count < MAX) count++; else Console.WriteLine("Max array size exceeded. Roll off the end."); Console.WriteLine("count=" + count + ", Push = " + data); } else { count++; stack[MAX - 1] = data; Console.WriteLine("count=" + count + ", Push = " + data); } } internal string Pop() { if (count > 0) count--; else return stack[MAX - 1]; string popValue = stack[MAX - 1]; //pop value on top of array Console.WriteLine("count = " + count + ", Pop = " + popValue); for (int i = MAX - 1; i >= 1; i--) //inline copy fast { stack[i] = stack[i - 1]; } stack[0] = "empty"; //initialize bottom of stack, gets empty string return popValue; } internal string Peek() //traditional definition of top { return stack[MAX - 1]; } internal string Top() { return stack[MAX - 1]; } internal void PrintTop() { Console.WriteLine("The topmost element of Stack is : {0}", stack[MAX - 1]); } internal void PrintStack() { Console.WriteLine("Printing Stack with {0} items:", count); for (int i = MAX - 1; i >= 0; i--) { Console.Write("arr[" + i + "]=" + stack[i] + ","); } Console.WriteLine(); Console.WriteLine(); } } public static class Program { public static void Main() { Stack s = new Stack(); Console.WriteLine("Pop/Push Array Test"); Console.WriteLine("Arr Len = " + s.Length().ToString()); Console.WriteLine("Top of stack is at index = " + (s.Length()-1).ToString()); s.PrintTop(); s.PrintStack(); s.Push("a"); s.PrintTop(); s.PrintStack(); s.Push("b"); s.PrintTop(); s.PrintStack(); s.Push("c"); s.PrintTop(); s.PrintStack(); s.PrintStack(); s.Push("d"); s.PrintTop(); s.PrintStack(); s.Push("e"); s.PrintStack(); s.PrintTop(); s.Push("f"); s.PrintStack(); s.PrintTop(); s.Push("g"); s.PrintStack(); s.PrintTop(); Console.WriteLine("Item popped from Stack : {0}", s.Pop()); s.PrintStack(); Console.WriteLine("Item popped from Stack : {0}", s.Pop()); s.PrintStack(); Console.WriteLine("Item popped from Stack : {0}", s.Pop()); s.PrintStack(); Console.WriteLine("Item popped from Stack : {0}", s.Pop()); s.PrintStack(); Console.ReadKey(); } } }

1st version below
This investigates using Array.Copy as Microsoft's own C# solution for Stack implementation, but is slow, compared to method above.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89

using System;using System.Diagnostics;using System.Linq;public static class Program { public static void PushStringCopyArray(ref string[] array, string pushvalue) { string[] temp = new string[array.Length]; temp[0] = pushvalue; Array.Copy(array, 0, temp, 1, array.Length - 1); array = temp; } public static void PushStringArray(ref string[] array, string pushvalue) { int newLength = array.Length; string[] temp = new string[array.Length]; temp[0] = pushvalue; //push new value on top of array for (int i = 0; i < array.Length - 1; i++) temp[i + 1] = array[i]; array = temp; } /// <summary> /// Pop value from top of string[] ref array /// </summary> public static string PopStringArray(ref string[] array) { int newLength = array.Length; //string[] temp = new string[array.Length]; //default value is "" string[] temp = Enumerable.Repeat("#", array.Length).ToArray(); //set a default value string popvalue = array[0]; ////push new value on top of array for (int i = array.Length - 1; i >= 1; i--) temp[i - 1] = array[i]; array = temp; return popvalue; } public static void PrintArray(ref string[] array) { for (int i = 0; i < array.Length; i++) Console.Write("a[" + i + "]=" + array[i] + ","); Console.WriteLine(); Console.WriteLine(); } public static void Main() { Stopwatch sw = new Stopwatch(); string[] test = new string[] {"z","a","b","c"}; Console.WriteLine("Pop/Push Array Test"); Console.WriteLine("Arr Len=" + test.Length); PrintArray(ref test); PushStringArray(ref test, "1st"); PrintArray(ref test); PushStringArray(ref test, "2nd"); PrintArray(ref test); PushStringArray(ref test, "3rd"); PrintArray(ref test); sw.Start(); PushStringArray(ref test, "4th"); sw.Stop(); Console.WriteLine(sw.ElapsedTicks + " ticks. WOW! For loop, but still O(n)."); PrintArray(ref test); sw.Start(); PushStringCopyArray(ref test, "5th"); sw.Stop(); Console.WriteLine(sw.ElapsedTicks + " ticks. Array.Copy: I thought this would be better."); PrintArray(ref test); Console.WriteLine(PopStringArray(ref test)); PrintArray(ref test); Console.WriteLine(PopStringArray(ref test)); PrintArray(ref test); Console.WriteLine(PopStringArray(ref test)); PrintArray(ref test); Console.WriteLine(PopStringArray(ref test)); PrintArray(ref test); Console.WriteLine(PopStringArray(ref test)); PrintArray(ref test); } }

Generic Stack Implementation with timings https://docs.microsoft.com/en-us/dotnet/api/system.collections.stack?view=netcore-3.1