Python：将 print() 函数中的 None 值转换为字符串

Question

I am trying to write a function that takes a list value as an argument and returns a string with all the items separated by a comma and a space, with 'and' inserted before the last item.

For example, passing the list 'spam' which contains the values ['apples', 'bananas', 'tofu', 'cats'] , would return: "apples, bananas, tofu, and cats" .

I wrote the following code:

def thisIsIt(alist):
  alist.insert(-1, 'and')
  alist1 = alist[:-2]
  alist2 = alist[-2:]
  for item in alist1:
    print(item, end = ", ")

  for item in alist2:
    print(item, end = " ")

which does return: apples, bananas, tofu, and cats. However it is printed as a Nonetype, instead of a string. How can I correct this please?

Answer 1

In any case, if you want a different solution and want it to return a String you can use the power of str.join() in python:

def thisIsIt(alist):
  resultString = ", ".join(alist[:-2] + [" and ".join(alist[-2:])])
  return resultString

myList = ['apples', 'bananas', 'tofu', 'cats']
myListAsString = thisIsIt(myList)
print(myListAsString)
#apples, bananas, tofu and cats 

Answer 2

Code :

list_sample = ['apples', 'bananas', 'tofu', 'cats']

for i in range(0,len(list_sample)):
    if i < len(list_sample)-1 and i != len(list_sample)-2:
        print(list_sample[i],end = ", ")
    elif i == len(list_sample)-2:
        print(list_sample[i],end = " and ")
    else:
        print(list_sample[i])

Output :

apples, bananas, tofu and cats 

Answer 3

I have tried KISS . (Keep It Simple Stupid)

spam = ['apples', 'bananas', 'tofu', 'cats', 'oranges']

def newlist(x):
    myStr = ''    
    if len(x) != 0:
        for i in range(len(x)-1):
            myStr += str(x[i]+', ')
    return(myStr + 'and ' + x[-1]) 

newlist(spam)

I think for beginners like me try to keep things simple, guys!