如何增加字符串中间的数字？

Question

So, I have this string:

string = ("book_volume_2")

and I want to increase that number to 3, 4 and so on, up to 6

I've tried

book = ("book_volume_")
book_plus = (book + str(book +1))

I get something like

book_volume_2book_volume22

but I'm expecting:

book_volume_3

Is there any way to obtain this?

Thanks!

Answer 1

What you want to use are f-strings

for i in range(1,5):
    print(f'book_volume_{i}')

I've applied the logic in a for-loop to show how it works.

But basically, whatever is inside the curly brackets is not considered a string.

eg

if I have function myFunc:

def myFunc():
    return 5

And then I do print(f'book_volume_{myFunc()}')

The result will be: book_volume_5

Answer 2

You need to make the numeric part of the string an integer if you want to increment it. Assuming the book name and number are always separated by an underscore you could do something like:

mystr = "book_volume_2"
book, sep, vol = mystr.rpartition('_')
vol = str(int(vol) + 1)
my_new_str = ''.join([book, sep, vol])

> 'book_volume_3'

Answer 3

If you have a string string = "book_volume_2" where the last character is a digit, then you can replace that with the next number like this:

def next_number(book):
    base = book[:-1]
    digit = int(book[-1])
    return base + str(digit + 1)

print(next_number('book_volume_2'))

Answer 4

string = "book_volume_" + input('Enter volume number: ')
print(string)