Saving output of a loop to file

Question

I want to save the output (0,1,1,2,3) of for-loop to the file but my code writes just the last value (3) of loop. How can I fix it?

#!/usr/bin/python

def fib(n):
    a, b = 0, 1
    for i in range(0, n):
        a, b = b, a + b
    return a
for c in range(0, 5):
   print(fib(c))
   file=open("fib.txt","w")
   s = str(fib(c))
   file.write(s+"\n")
#   file.write("%s\n" % fib(c))
   file.close()

possible duplicate of [How do you append to a file in Python?](http://stackoverflow.com/questions/4706499/how-do-you-append-to-a-file-in-python) — Igl3, May 21 '15 at 10:15
When you open the file in writeable mode then it rewrites the contents use append mode instead. — ZdaR, May 21 '15 at 10:15
I suggest to open the file before the for loop and close the file after the loop. — Peter Paul Kiefer, May 21 '15 at 10:18

score 1 · Accepted Answer · edited May 21 '15 at 10:20

1

Try to this.

def fib(n):
    a, b = 0, 1
    for i in range(0, n):
        a, b = b, a + b
    return a
file=open("fib.txt", "a")
for c in range(0, 5):
   print(fib(c))
   s = str(fib(c))
   file.write(s + "\n")
file.close()

edited May 21 '15 at 10:20

ZdaR

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answered May 21 '15 at 10:16

Haresh Shyara

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Vincent · Answer 2 · 2015-05-21T10:39:15.693

1

You might want to read about generators and context managers:

def fib(n):
    a, b = 0, 1
    for i in range(n):
        a, b = b, a + b
        yield a

with open("fib.txt","w") as f:
    for x in fib(5):
        f.write(str(x) + '\n')

edited May 21 '15 at 10:39

answered May 21 '15 at 10:23

Vincent

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Looks like you beat me to it! – pzp May 21 '15 at 10:30

score 1 · Answer 3 · answered May 21 '15 at 10:24

Well its not only easy but far more easy then easy ... :P

use the same code just change the mode of file while opening that is...

file=open("fib.txt","w") #opens your file in write mode

so.. change it to

file=open("fib.txt","a") #opens your file in append mode

which will open your file in append mode.

score 0 · Answer 4 · answered May 21 '15 at 10:21

Give a try to yield instead of return

#!/usr/bin/python

def fib(n):
    a, b = 0, 1
    for i in range(0, n):
        a, b = b, a + b
        yield a
for c in range(0, 5):
   print(fib(c))
   file=open("fib.txt","w")
   for s in str(fib(c)):
       file.write(s+"\n")
   file.close()

Saving output of a loop to file

4 Answers4