如何通过嵌套循环在python中创建一个*框？

Question

I'm trying to create a *box through nested loop. So How I can create box?

I've tried to create a logic through some division, multiplication, subtraction, modules.I don't what is problem?

for colm in range(1,5):
    print('* ',end='')
    for row in range(1,21):
        if (colm==1) or (colm==4) or (row==20  and colm==2) or (row==20 and colm==3) :
            print('*',end=' ')
    print('')

Output:

* * * * * * * * * * * * * * * * * * * * * 
* * 
* * 
* * * * * * * * * * * * * * * * * * * * *  

I expected:

* * * * * * * * * * * * * * * * * * * * * 
*                                       *  <---- I want * here.
*                                       *  <---- I want * here.
* * * * * * * * * * * * * * * * * * * * *

Answer 1

rows = 5
cols = 23
for i in range(rows):
    print('*' + ('*' if i in (0,rows-1) else ' ') * (cols-2) + '*')

output

***********************
*                     *
*                     *
*                     *
***********************

All rows start and end with an asterisk, and only the top and bottom fill, the middle rows all use spaces instead.

Answer 2

You need to fill in the missing space with something - your writing cursor is always after the last character, it doesn't magically move sideways.

Also, you can use replicating strings instead of the inner loop to get rid of if s:

print("*" * columns)
for row_no in range(rows-2): # -2 because we print top and bottom row differently
    print("*" + " "*(columns-2) + "*")

print("*" * columns)

Answer 3

Try this

def print_rectangle(n, m) : 

    for i in range(1, n+1) : 
        for j in range(1, m+1) : 
            if (i == 1 or i == n or
                j == 1 or j == m) : 
                print("*", end="")             
            else : 
                print(" ", end="")             

        print() 


# Driver program for above function 
rows = 6 # Breadth of your Quadrilateral
columns = 20 #Length of your Quadrilateral
print_rectangle(rows, columns) 

The driver part of the program can be run-time based if you want, to do that you need to take integer input from the user.

rows= int(input("Enter the breadth of your Quadrilateral"))

Now let's understand what happens when you call the print_rectangle(rows, columns)

The part that you need to understand is this

for i in range(1, n+1) : 
            for j in range(1, m+1) : 
                if (i == 1 or i == n or
                    j == 1 or j == m) : 
                    print("*", end="")             
                else : 
                    print(" ", end="")

In simple language, if you observe the structure you want it to have * if it is the 1st column or the nth column OR if it the 1st row or the nth row

So the outer loop takes care of columns

 for i in range(1, n+1)

and the inner loop takes care of the number of rows.

for j in range(1, m+1)

Now you must relate the variable i with row-number and j with column-number and then read the if clause . You will find it says the same thing I explained above in terms of English words .

If you need further clarification, I'll be happy to elaborate it for you if you let me know where you are having trouble.

Answer 4

You can use a simple algorithm to print box shapes

1. Define the length and breadth of the box(rows and columns).
2. Loop through rows and columns

3. For row

   • If the row item(i in our case is i==0 or i==row, then print '*' except print space .
   • this will print our left and right side of the box.

4. For columns

   • If the columns item(j in our case is j==0 or j==columns, then print '*' except print space .
   • this will print our top and bottom side of box.

Note: we used **end=''** to prevent newline after printing '*' or space

def box(rows, columns):
    for i in range(1, rows + 1):
        for j in range(1, columns + 1):
            if (i == 1 or i == rows or j == 1 or j == columns):
                print('*', end='  ')
            else:
                print(' ', end='  ')
        print()

square

>>> box(10,10)
*  *  *  *  *  *  *  *  *  *  
*                          *  
*                          *  
*                          *  
*                          *  
*                          *  
*                          *  
*                          *  
*                          *  
*  *  *  *  *  *  *  *  *  *  

rectangle

>>> box(10,5)
*  *  *  *  *  
*           *  
*           *  
*           *  
*           *  
*           *  
*           *  
*           *  
*           *  
*  *  *  *  *