Python adding an integer to a list

Question

I am trying to add 1 to my variable and then add this variable to a list so when I print out my list, the value of the variable is within it. However, my code prints out an empty list despite me adding the variable to it.

case_number = 0
case_numbers = []
issue = input('Has the issue been solved?').lower()
if issue == 'no':
 case_number += 1
 case_numbers+[int(case_number)]
 print(case_numbers)

• Moses Koledoye: + creates a new list which you're discarding. What you want is case_numbers.append(int(case_number))
• Tom de Geus: You need to replace the final before last line with case_numbers+=[int(case_number)]
• Serenity: You have a misprint, write case_numbers+=[int(case_number)] (forgot the equal)
• Martijn Pieters: or use case_numbers.append(...).
• roganjosh: case_numbers.append(int(case_number)) is the standard way. The reason your approach doesn't change the list is that you don't assign the modified list back to case_numbers e.g. case_numbers = case_numbers + [int(case_number)]

Answer 1

If you want to add a value to a growing list you need to use list.append() method. It adds the value to the end of the list, so you code should be:

case_number = 0
case_numbers = []
issue = input('Has the issue been solved?').lower()
if issue == 'no':
 case_number += 1
 case_numbers.append(int(case_number))
 print(case_numbers)

Extra tip: list.append() method adds value to end of list so if you add the list B into list A using append() then it will add the listB inside the listA like this listA.append(listB)= ["a","b","c",["d","e","f"]] so if you want to add the values as normal list you should use list.extend() method which will add the values of one list to another such that listA.extend(listB)=["a","b","c","d","e","f"]

Answer 2

if issue == 'no':
 case_number += 1
 case_numbers.append(case_number)
 print(case_numbers)

Here, case_numbers.append(case_number) statements add the elements to the list.

Answer 3

The issue is with this line:

case_numbers+[int(case_number)]

While it's true that you can append values to a list by adding another list onto the end of it, you then need to assign the result to a variable. The existing list is not modified in-place. Like this:

case_numbers = case_numbers+[int(case_number)]

However, this is far from the best way to go about it. For a start, you don't need to convert your case_number value to an int, because it already is an int. Also, lists have an append method for this exact purpose.

case_numbers.append(case_number)

Answer 4

Try using append or insert :

insertis used like the following :

case_numbers.insert(0,case_number) #will insert it at first

or append like this :

case_numbers.append(case_number)

check this link : http://www.thegeekstuff.com/2013/06/python-list/?utm_source=feedly