What does python stack mean?

What does python stack mean?

The stack is a special list. The elements in the stack can only Access is through one end of the list, which is called the top of the stack. The stack is called a last-in-first-out (LIFO, last-in-first-out) data structure.

Since the stack has the last-in-first-out characteristic, any element that is not at the top of the stack cannot be accessed. In order to get the element at the bottom of the stack, the element above must first be removed.

The two main operations on the stack are pushing an element onto the stack and popping an element off the stack. Use the push() method to push onto the stack, and pop() to pop out of the stack.

Another commonly used operation is to preview the element at the top of the stack. Although the pop() method can access the element on the top of the stack, after calling this method, the element on the top of the stack is also permanently deleted from the stack. The peek() method only returns the top element of the stack without deleting it.

In order to record the position of the top element of the stack, and also to mark where new elements can be added, we use the variable top. When an element is pushed into the stack, the variable increases; when an element is popped from the stack, The variable decreases.

push(), pop() and peek() are the three main methods of the stack, but the stack has other methods and attributes.

stack Usual operations:

Stack()    建立一个空的栈对象
push()     把一个元素添加到栈的最顶层
pop()      删除栈最顶层的元素，并返回这个元素
peek()     返回最顶层的元素，并不删除它
isEmpty()  判断栈是否为空
size()     返回栈中元素的个数

Simple case and operation results:

Use python list here Implementation of object simulation stack:

class Stack: 
    """模拟栈""" 
    def __init__(self): 
        self.items = [] 

    def isEmpty(self): 
        return len(self.items)==0  

    def push(self, item): 
        self.items.append(item) 

    def pop(self): 
        return self.items.pop()  

    def peek(self): 
        if not self.isEmpty(): 
            return self.items[len(self.items)-1] 

    def size(self): 
        return len(self.items)

Create a stack object and add operation methods:

s=Stack() 
print(s.isEmpty()) 
s.push(4) 
s.push('dog') 
print(s.peek()) 
s.push(True) 
print(s.size()) 
print(s.isEmpty()) 
s.push(8.4) 
print(s.pop()) 
print(s.pop()) 
print(s.size())

Related recommendations: "Python Tutorial"

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