Write each prime number in different line (Python 3)

Question

I would like to write random prime numbers in new lines to a text file, but when I run my script it writes all numbers in one line. It's very likely that I don't understand something correctly.

This is my original code:

import random
file = open("prime.txt", "w")
i = 0
while( i<=100 ):
    temp=str(random.randint(1, 500) )
    file.writelines(temp)
    i += 1
file.close()

According to the answers, I just have to use the write() method with newline character ( \\n ) instead of the writelines() method.

Answer 1

writelines doesn't add line separators (which seems weird considering readlines removes them). You'll have to add them manually.

lines = ['{0}\n'.format(random.randint(1,500)) for i in range(100)]
file.writelines(lines)

Answer 2

You need to pass a sequence to writelines, you can use a generator expression and also use with to open your files replacing your while loop with a range :

import random
with  open("prime.txt", "w") as f:
   f.writelines(str(random.randint(1,500))+"\n" for _ in range(100))

Answer 3

You can just add a newline when writing each number to the file. Also use file.write() instead of file.writelines() . Just use this as your code:

import random
file = open("primes.txt", "w")
i=0
while(i<=100):
    temp=str(random.randint(1,500))
    file.write(temp  + "\n")  #add a newline after each number
    i+=1
file.close()