“如何修改以下程序，使其以特定格式打印？”

Question

I am trying to modify the below program so it prints the string in the following format

input : Fred, 4

output :

Fred

Fred Fred

Fred Fred Fred

Fred Fred Fred Fred

There are 3 mistakes in this code:

def prlines(str, num):

    n in range(0,num):

    print (str (n + 1))


prlines()

So I already tried the following code:

name=str(input('Enter a name:'))  
num=int(input('Enter a number:'))  

 def prlines(str, num):  

    for n in range(0, num):

      print(str*(n + 1))

 print(prlines(name, num))

I get this Actual Results (eg with the Name 'Fred' and the Number '4'):

Fred

FredFred

FredFredFred

FredFredFredFred

None

My question is How can I get the expected results to display with the following constraints:

• without None at the end

• with spaces between the strings

Answer 1

You can use:

f'{s} ' * n + f'{s}'

Code :

name = input('Enter a name: ')
num = int(input('Enter a number: '))

def prlines(s, num):
    for n in range(num):
        print(f'{s} ' * n + f'{s}') 

prlines(name, num)

Few points :

• Don't name variable as str .

• A function by default with no return , returns None , hence you have a None at the end.

Answer 2

First

Code Analysis

name=str(input('Enter a name:'))  
num=int(input('Enter a number:'))  

def prlines(str, num):  

    for n in range(0, num):

        print(str*(n + 1)) # No spaces added = No spaces on the output

print(prlines(name, num)) # You are printing the output of the above function, which is None since it has no "return"

The print(func()) is where you get your None from

Since you are only printing the str multiple times, you didn't include spaces (python won't know :)

Answer

name=str(input('Enter a name:'))  
num=int(input('Enter a number:'))  

def prlines(str, num):  
    for n in range(0, num):
        print((str+' ')*(n + 1))

prlines(name, num)

Advice

This code is quite rough, you would need to think about error handling when someone doesn't input an int in the second input.