CODEWITHSUNDEEP
pythonstringloops
user6942654
user6942654

Reputation:

Best way to write a string without "rewriting it" each loop iteration

I'm trying to write a new string with a for loop but each time the loop goes through an iteration, the string gets rewritten with the new iteration. Is there any way to prevent this?

for i in range(0,len(string1)):
    newString = string1[i] + string2[i]
return newString

newString only comes out as the last iteration when I need to newString to be the first iteration to the last.

Upvotes: 0

Views: 45

Answers (1)

Robᵩ
Robᵩ

Reputation: 168636

If you want to accumulate all of per-iteration values, try using the aggregate assignment operator +=. The following code will return one very long string, which is the concatenation of all of the intermediate strings.

newString = ''
for i in range(0,len(string1)):
    newString += string1[i] + string2[i]
return newString

Alternatively, you might want to return a list of the intermediate values, like so:

newList = []
for i in range(0,len(string1)):
    newList += [string1[i] + string2[i]]
return newList

Note, however, that it is often a bad idea to append strings in a loop. It causes a lot of memory reallocation. The typical Pythonic form is to collect the intermediate values into a list and ''.join() them together, like so:

newList = []
for i in range(0,len(string1)):
    newList += [string1[i] + string2[i]]
newString = ''.join(newList)
return newString

Equivalently, and more compactly,

return ''.join(''.join(chars) for chars in zip(string1, string2))

Upvotes: 3

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