使用.txt文件行的内容作为python3变量的输入

Question

I have a python script which print in a text file every prime. I would like my script to pickup the list where it left off so basically take the contents of the last line as a variable.

Here is my current script:

def calc():
    while True:
        x = 245747
        y = (100**100)**100
        for n in range (x,y):
            if all(n%i!=0 for i in range (2,n)):
                a=[]
                a.append(n)
                fo = open('primes.txt', 'a+')
                print(n)
                print ("", file = fo)
                print ((a), file = fo)
                fo.close
        s = input('To do another calculation input yes, to quit input anything else...')
        if s == 'yes':
            continue
        else:
            break
calc()

I would like the variable x to get as an input the last line of primes.txt There should be on that last line "[245747]" if the greatest prime number is 245747.

How could I achieve that? Thanks!

Answer 1

You can do use readlines and get the last item of the list:

file = open("primes.txt", "r").readlines()
x = file[len(file)-1]

I think this should work. You can just get rid of the 2 "[" and "]" with split or something similar.