string - Confusion in file functioning and append function using Python -

i have 2 questions exam.

t2=("a","b","hello") alist=["barney",["wilma"]] print(alist[1].append(t2)) 

answer:

none 

i thought [“wilma”,(“a”,”b”,”hello”)]

and

file has:

james,8,9 sonia,7,6 clark,4,5 

code:

endofprogram=false try:     infile=open("names.txt",”r”) except ioerror:     print("error reading file")     endofprogram=true if endofprogram==false:     line in infile:         line.strip('\n')         alist=line.split(',')         print(alist) 

answer

['james','8','9\n'] ['sonia','7','6\n'] ['clark','4','5\n'] 

why '\n' still there? lastly:

def change(alist):     alist=alist.pop()     alist.append(5)     return def main():     mylist=[1,2,[3]]     change(mylist)     print(mylist) main() 

answer:

[1,2] 

why answer? shouldn't [1,2,5]?

• list.append in-place operation, modifies list in-place , returns none.

>>> lst = [] >>> repr(lst.append(1)) #returns none 'none' >>> lst                 #list modified [1] 

• strings immutable, need re-assign result of .strip() call variable.

line = line.strip('\n') #re-assign new returned string variable. alist = line.split(',') 

• you re-assigned alist different list, .append() call won't affect passed list.

def change(alist):     alist = alist.pop() #now alist points [3] not `[1, 2, [3]]`     alist.append(5) 

you can use assignment statement here:

alist[-1] = 5