Python can't open file "No such file or directory"

Question

def main():
    fh = open('lines.txt')
    for line in fh.readlines():
        print(line)

if __name__ == "__main__": main()

Directory files

I am on for-working.py file, and am trying to access the lines.txt file within the same working directory. But I get error

No such file or directory: 'lines.txt'

Does python need to have an absolute path when opening files?

why doesn't this relative path work here?

Running python 3.6

EDIT ^1 I'm running visualstudio code with the python package extension by Don Jayamanne, and "Code Runner" package to compile/execute python code

EDIT ^2 Full error:

Traceback (most recent call last):
  File "c:\www\Ex_Files_Python_3_EssT(1)\Ex_Files_Python_3_EssT\Exercise Files\07 Loops\for-working.py", line 11, in <module>
    if __name__ == "__main__": main()
  File "c:\www\Ex_Files_Python_3_EssT(1)\Ex_Files_Python_3_EssT\Exercise Files\07 Loops\for-working.py", line 7, in main
    fh = open('lines.txt', 'r')
FileNotFoundError: [Errno 2] No such file or directory: 'lines.txt'

EDIT ^3 checking sys.path

import sys
print(sys.path)

produces this information:

['c:\\www\\Ex_Files_Python_3_EssT(1)\\Ex_Files_Python_3_EssT\\Exercise Files\\07 Loops', 
'C:\\Users\\Kagerjay\\AppData\\Local\\Programs\\Python\\Python36\\python36.zip', 'C:\\Users\\Kagerjay\\AppData\\Local\\Programs\\Python\\Python36\\DLLs', 'C:\\Users\\Kagerjay\\AppData\\Local\\Programs\\Python\\Python36\\lib', 'C:\\Users\\Kagerjay\\AppData\\Local\\Programs\\Python\\Python36', 'C:\\Users\\Kagerjay\\AppData\\Local\\Programs\\Python\\Python36\\lib\\site-packages']

EDIT ^4 checking os.getcwd()

Running

import os
print(os.getcwd())

Produces

c:\www\Ex_Files_Python_3_EssT(1)\Ex_Files_Python_3_EssT\Exercise Files

Well its definitely not in the right subdirectory (needs to cd 07 loops folder, that narrows the issue down

EDIT ^5 what is in lines.txt file

My lines.txt file i am opening looks like this. No extra whitespace or anything at start

01 This is a line of text
02 This is a line of text
03 This is a line of text
04 This is a line of text
05 This is a line of text

IN SUMMARY

Visual studio code's Code runner extension needs to be tweaked slightly to open files within a subdirectory so any of the below answers would provide a more robust solution to be independent of any extension / dependencies with the IDE

import os
print(os.getcwd())

Is most useful for diagnosing problem to the current directory python interpreter sees

Answer 1

Get the directory of the file, and join it with the file you want to open:

def main():
    dir_path = os.path.dirname(os.path.realpath(__file__))
    lines = os.path.join(dir_path, "lines.txt")
    fh = open(lines)
    for line in fh.readlines():
        print(line)

if __name__ == "__main__": main()