此方法(位于System.Collections命名空间下)用于在Stack的顶部插入一个对象。如果Count已经等于容量，则通过自动重新分配内部数组来增加Stack的容量，并在添加新元素之前将现有元素复制到新数组。如果Count小于堆栈的容量，则Push是O(1)运算。如果需要增加容量以容纳新元素，则Push变为O(n)操作，其中n为Count。
句法：
public virtual void Push (object obj);
例子：
// C# code to demonstrate the
// Stack.Push() Method
using System;
using System.Collections;
class GFG {
// Driver code
public static void Main()
{
// Creating a Stack
Stack myStack = new Stack();
// Inserting the elements into the Stack
myStack.Push("one");
// Displaying the count of elements
// contained in the Stack
Console.Write("Total number of elements "+
"in the Stack are : ");
Console.WriteLine(myStack.Count);
myStack.Push("two");
// Displaying the count of elements
// contained in the Stack
Console.Write("Total number of elements"+
" in the Stack are : ");
Console.WriteLine(myStack.Count);
myStack.Push("three");
// Displaying the count of elements
// contained in the Stack
Console.Write("Total number of elements"+
" in the Stack are : ");
Console.WriteLine(myStack.Count);
myStack.Push("four");
// Displaying the count of elements
// contained in the Stack
Console.Write("Total number of elements"+
" in the Stack are : ");
Console.WriteLine(myStack.Count);
myStack.Push("five");
// Displaying the count of elements
// contained in the Stack
Console.Write("Total number of elements"+
" in the Stack are : ");
Console.WriteLine(myStack.Count);
myStack.Push("six");
// Displaying the count of elements
// contained in the Stack
Console.Write("Total number of elements"+
" in the Stack are : ");
Console.WriteLine(myStack.Count);
}
}
输出：
Total number of elements in the Stack are : 1
Total number of elements in the Stack are : 2
Total number of elements in the Stack are : 3
Total number of elements in the Stack are : 4
Total number of elements in the Stack are : 5
Total number of elements in the Stack are : 6
参考：
- https://docs.microsoft.com/ena-us/dotnet/api/system.collections.stack.push?view=netframework-4.7.2