PYTHON and variables?

 PYTON does not work with variables. PYTON works with:
- name,
- objects,
- types,
- values,
- reference number.
If we write:
a = 7
then:
- a is the name
- a PYTHON object corresponding to the name a is created
- 7 is value
- the type is whole
- the reference count is 0.
if we write below
a = 100
then:
- remain the same name,
- a new object associated with the name a is created,
- the type is integer,
- the reference count is 1
This explains the different addresses id (a) from the first assignment and from the second assignment.
Programe is:
a = 7
print(id(a))
a = 100
print(id(a))

Results are:

============== RESTART: /Users/ionivan/Documents/pointerspython.py =============
4408295856
4408298832
If the sequence is considered:
a = 25
b = a
the names a and b correspond to the same object, so they will have the same address.
Programul este:
a = 25
b = a
print("Adress a name is",id(a))
print("Adress b name is",id(b))

Rezultatele sunt:

============== RESTART: /Users/ionivan/Documents/pointerspython.py =============
Adresse a name is 4480173040
Adresse b name is 4480173040

Rorograme is:

list_A = [2, 3, 4, 5, 6, 7, 8, 9, 10]
print("list_A is", list_A)
print("Adresse list_A is", id(list_A))
print("Adresse list_A[8] is", id(list_A[8]))
list_A.append(11)
print("list_A  after append is", list_A)
print("Adress list_A after append is", id(list_A))
print("Adresse list_A[9] is", id(list_A[9]))
list_A.insert(0, 20)
print("list_A  after insert is", list_A)
print("Adress list_A[10] after insert is", id(list_A[10]))

Results are:
list_A is [2, 3, 4, 5, 6, 7, 8, 9, 10]
Adresse list_A is 4363290752
Adresse list_A[8] is 4360651280
list_A  after append is [2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
Adress list_A after append is 4363290752
Adresse list_A[9] is 4360651312
list_A  after insert is [20, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
Adress list_A[10] after insert is 4360651312

There are big differences between working in C ++ and PYTHON. Programmers who have worked in C ++ use the concept of variable, but in PYTHON it is correct to use names.

(March 31, 2022)

Comments

Post a Comment

Popular posts from this blog

Functions and many return parameters

Programe is:  # #   functions and many return parameters # def function_1(a,b):     return a+b def function_2(a,b):     suma = a + b     if a > b:         minimum =b     else:         minimum = a     return suma, minimum def function_3(a,b):     suma = a + b     if a > b:         minimum = b     else:         minimum = a     if a > b:         maximum = a     else:         maximum = b     return suma, minimum, maximum X = 10 Y = 20 Z = function_1(X,Y) W, V = function_2(X,Y) A, B, C = function_3(X,Y) print(' If a=', X,  'and b= ', Y, 'than a+b=', Z) print(' If a=', X,  'and b= ', Y, 'than a+b=', W, 'minumum is', V ) print(' If a=', X,  'and b= ', Y, 'than a+b=', A, 'minumum is', B,       'and maximum is', C)...
Read more

Functions list in PYTHON

Programe is: # #    Functions list # def print_1(Word,val):  #  print string function     Alfa = Word[val-1]     print(Alfa)     return  def sum_x(x,nr):   # add list elements function     s =0     for i in range(nr):         s+= x[i]     return s def norma_a(a,nr):  # add absolute value list elements function     norm = 0     for i in range(nr):         norm += abs(a[i])     return norm functions = [print_1, sum_x, norma_a]    # functions list results = [0,0,0] WORD = ["aaaa", "bbbb", "cccc", "dddd","eeee",         "ffff", "gggg", "hhhh", "mmmm","nnnn"] X = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] A = [1, -2, 3, -4, 5, -6, 7, -8, 9, -10] NR = [10, 10, 10] NRR =3 i = 0 parameters = [WORD, X, A] for ijj in (functions):     results[i] = ijj(parameters[i], NR[i])     print (results[...
Read more
 Prorgram is: # #           Equality elements lists, sets, dictionaries # Elem_A = 10 Elem_B = 10 Elem_C = 15 List_A = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] List_B = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] List_C = [1,2,3,3,3,6,7,8,9,10] Set_A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} Set_B = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} Set_C = {1, 2, 3, 3, 3, 3, 7, 8, 9, 10} Dictionary_A = {1:1, 2:2, 3:3, 4:4, 5:5, 6:6, 7:7, 8:8, 9:9, 10:10} Dictionary_B = {1:1, 2:2, 3:3, 4:4, 5:5, 6:6, 7:7, 8:8, 9:9, 10:10} Dictionary_C = {1:1, 2:2, 3:3, 4:3, 5:3, 6:3, 7:7, 8:8, 9:9, 10:10} def compare(X,Y):     if X == Y:         Alfa = True     else:         Alfa = False     return Alfa print(' Element equality') Elem_Test_AB = compare(Elem_A,Elem_B) print('Element A is equal to element B? Result is:', Elem_Test_AB) Elem_Test_AC = compare(Elem_A,Elem_C) print('Element A is equal to element C? Result is:', Elem_Test_AC) print(' Lis...
Read more