Print 2D Array

[dragu_stelian]

Hello!
I am new in Python and I have a question.
In the next code I want to print a 2D array in "C++ style"

tab = [[]]
rows = int(input("Enter size of the rows: "))
cols = int(input("Enter size of the cols: "))

for i in range(0, rows):
    for j in range(0, cols):
        arr = int(input("tab[{}][{}] = ".format(i,j)))
        tab.append(arr)

print()
for i in range(len(tab)):
    print(tab[i], end = " ")
print()

For a tab[2][3] the below code will print:

Enter size of the rows: 2
Enter size of the cols: 3
tab[0][0] = 11
tab[0][1] = 12
tab[0][2] = 13
tab[1][0] = 21
tab[1][1] = 22
tab[1][2] = 23

[] 11 12 13 21 22 23

Why square brackets at the beginning ?
There are many ways to print the 2D array in Python ?

[buran]

To answer your question - on line 1 you initialize the tab list with empty list, i.e. your tab list already has 1 element before you input rest values and append them to tab list.
make line 1

tab = []

However I don't think the result is what you expect - tab is a list, not list of lists if that is what you expect

[perfringo]

What datastructure you want to build?

I assume that 2D array is list of lists (matrix). If so, you can create in several ways. Some examples:

>>> matrix = []                                   # create empty list named matrix
>>> for i in range(3):
...     matrix.append([])                         # append empty list to end of matrix
...     for j in range(4):
...         matrix[-1].append(0)                  # append zeros to last list of matrix
...
>>> print(matrix)
[[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]        # matrix with three rows and four columns

It can be done with list comprehension with one-liner:

>>> [[0 for i in range(4)] for j in range(3)]
[[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]

Matrix with consecutive numbers with asking from user number of rows and columns:

rows = int(input('Number of rows: '))
cols = int(input('Number of columns: '))
mtx = [[i + cols * j for i in range(1, cols + 1)] for j in range(rows)]
print(mtx)

In case of three rows and four columns this will print [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]

Sometime there is need for creating matrices with random numbers in it. In these cases utility functions like below can be handy:

def matrix_with_double_digits(rows, cols):
    return [[random.choice(range(10,100)) for i in range(cols)] for j in range(rows)]

This will generate matrix with specified number of rows and columns populated with random two-digit numbers.

[aakashjha001]

# this is one approach to create a 2D list in python.
#There are multiple ways of creating.
n = int(input())
a = []
for i in range(n):
row = input().split()
for i in range(len(row)):
row[i] = int(row[i])
a.append(row)
print(a)