Why does concatenation wrap part of the string?

Question

Python

with open('img.log', 'r') as f:
    contents = f.readlines()

for line in contents:
    img = line[45:]
    print(img + '.png')

at the output I get

1
.png
2
.png
3
.png

and it would be necessary for further work

1.png
2.png
3.png

otherwise the files are not found

Answer 1

Because the lines contain a line break character. Call .strip()to remove these characters. Or immediately read the file differently, for example

with open('img.log', 'r') as f:
    contents = f.read().splitlines()