为什么我的变量没有被访问？ 以及为什么我的输出会聚集在一起而不是在新行中返回

Question

I am trying to write a program which returns the even and odd strings sliced together. On doing so while compilation the "odd" variable that i have defined inside my "else:" statement is not accessible. what could be the problem? '''

       num = int(input())
        even_L = []
        odd_L = [] 

     for stdin in range(num):
       s = input()
       inputs = [n for n in s]

    for names in inputs:
       for name in range(len(names)):
          if name % 2 == 0:
              even_L.append(s[name])
              even = "".join(even_L)
         else:
              odd_L.append(s[name]) 
              odd = "".join(odd_L)

         new = even + 2 * " " + odd

#I have tried moving the indentation also

    print (new)

''' The error shown is : '''

Traceback (most recent call last):
    File "Solution.py", line 18, in <module>
   new = even + 2 * " " + odd
 NameError: name 'odd' is not defined

'''

And

I tried to do it in various ways. But even when i successfully arrange the strings. Since I had to input 2 names and the output should also return two names. But here it returns two names but the names had to be separated right? '''

let's say two names i.e. Hacker, Rank
the required output is: Hce  akr and Rn  nk

but mine output is Hce akr and HceRn  akrnk

   why does the second output comes paired with first output?

'''

My code for the problem is:

num = int(input())

even_strings = []
odd_strings = []
rev_nam = []
final_name = []

for i in range(num):
    S = input()
    rev_nam.append(S)

for name in rev_nam:
    for i in range(len(name)):
        if i%2 == 0:
            even_strings.append(name[i])
        else:
            odd_strings.append(name[i])

        even_formatted_string = "".join(even_strings)
        odd_formatted_string = "".join(odd_strings)

        names = even_formatted_string + 2 * " " + odd_formatted_string
    print(names)

OUTPUT :

Hce  akr
HceRn  akrak

Required Output:

Hce akr
Rn ak

I tried clearing the input after importing os module and using

os.system('cls')

but it doesn't seem to work or maybe i don't know where to place it. Any refrences

Answer 1

Your "odd" variable declaration is inside the else block and will only be accessed at runtime, if you don't get into the else block your variable wouldn't exist. Give it some default value outside the else block.

Answer 2

I found the answer to my question. The reason both variables were added was due to declaration of strings as global variables. So to re-iterate over the strings i had to declare the variables in local-scope.

num = int(input())

for stdin in range(num):
    s = input()   
    new = ''
    odd = ''
    even = ''
    for name in range(len(s)):
        if name % 2 == 0:
            even += s[name]
        else: 
            odd += s[name]   
        new = (even +" " + odd)

    print(new)

After doing this the output prompted as soon as i entered the input.