Python program to implement stack Operation :
In Python, we can use Lists to implement stacks. Python offers us a convenient set of methods to operate lists as stacks. For various stack operations, we can use a list say Stack and use Python code as described below: also given download link of stack project file.
Stack Operation
- Peek
- Push
- Pop
1.Peek - We can use <Stack> [top]
where <Stack is a list; top is an integer having value equal to len(<Stack) - 1.
2.Push - We can use <Stack.append(<item>)
where <item is the item being pushed in the Stack.>
3.Pop - We can use <Stack>.pop()
it removes the last value from the Stack and returns it
Let us now implement a stack of numbers through a program.
Full project file download link given below
Stack implementation in Python
def Push(stk, item):stack implementation
stack:implemented as a list
top:integer having position at topmost element in stack
def isempty(stk):
if stk==[]:
return True
else:
return False
def push(stk,item):
stk.append(item)
top=len(stk)-1
def pop(stk):
if isempty(stk):
return "Underfow"
else:
item=stk.pop()
if len(stk)==0:
top=None
else:
top=len(stk)-1
return item
def peek(stk):
if isempty(stk):
return "Underflow"
else:
top=len(stk)-1
return stk[top]
def display(stk):
if isempty(stk):
print("stack empty")
else:
top=len(stk)-1
print(stk[top],"<<<<top")
for a in range(top-1,-1,-1):
print(stk[a])
#_main_
stack=[] #initially stack is empty
top=None
while True:
print("STACK OPERATIONS")
print("1.PUSH")
print("2.POP")
print("3.PEEK")
print("4.DISPLAY STACK")
print("5.EXIT")
ch=int(input("Enter your choice(1-5):"))
if ch==1:
item=int(input("Enter Item:"))
push(stack,item)
elif ch==2:
item=pop(stack)
if item=="Underflow":
print("Underflow!!Stack is empty.")
else:
print("Popped item is", item)
elif ch==3:
item=peek(stack)
if item=="Underflow":
print("Underflow!! Stack is empty")
else:
print("Topmost item is:",item)
elif ch==4:
display(stack)
elif ch==5:
break
else:
print("INVALID CHOICE!!")
