Error in reading numbers from a file (Python)

Question

To start things off, this is my assignment(used on Python 3.4):

Here is my code. I think I have a pretty good hang of it:

# import random module
import random

# When doread() returns the maximum integer
# It is printed to the screen.
def main():
# call dowrite() and doread().
    dowrite()
    doread()

def dowrite():
    print ('Write will create 11 random numbers')
    print ('The number contained in mynumbers.txt are:')
    print('')
# generate random int num that is 5 < x < 13 and print num out
    random_int = random.randint(6, 12)
    print (random_int)
# use loop to generate num rand ints in range from 10-20 and write ints to mynumbers.txt.
# duplicates acceptable, w/ each int written to one line
myfile = open('mynumbers.txt', 'w')
for count in range(20):
        number = random.randint(10, 20)
        myfile.write(str(number) + '\n')

def doread():
# open the mynumbers.txt and read all numbers from file using for loop
    myfile = open('mynumbers.txt', 'r')
#    line = myfile.readline()
# Read each line in the file and display
for line in myfile:
    print(line)
# Print each number as it is read and find the largest number.
    with open('mynumbers.txt', 'r') as myfile:
        largest = max(map(int, myfile))
        print('The largest number in the file is: ',largest)

# Close the file and return largest number
myfile.close()

Again, as I said, I think I got the hang of it. Feel free to correct me otherwise, but my main problem is what happens when I press F5:

If someone could help me with this error, I could probably take it from here.

I think your identation is wrong, and you are not calling your main function. — Martín Muñoz del Río
– Martín Muñoz del Río, Commented Nov 7, 2015 at 2:25

Remi Guan · Accepted Answer · 2015-11-07 02:34:52Z

2

I'm sure that you're looking for something like this...

import random

def main():
    dowrite()
    doread()

def dowrite():
    print ('Write will create 11 random numbers')
    print ('The number contained in mynumbers.txt are:')
    print()

    # only need open the file once here, and we don't need print the numbers now
    with open('mynumbers.txt', 'w') as myfile:
        for count in range(20):
            number = random.randint(10, 20)
            myfile.write(str(number) + '\n')

def doread():
    # first we print all of the numbers in that file
    with open('mynumbers.txt', 'r') as myfile:
        for line in myfile:
            print(line.strip())
        print()

        # then, use seek() here to check the largest number
        myfile.seek(0)
        largest = max(map(int, myfile))
        print('The largest number in the file is: ', largest)

main() # don't forget call main function

Demo:

Write will create 11 random numbers
The number contained in mynumbers.txt are:

20
16
12
11
18
10
16
17
13
11
10
14
14
16
16
17
19
17
11
11

The largest number in the file is:  20

answered Nov 7, 2015 at 2:34

Remi Guan

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1 Comment

Baroness Sledjoys Over a year ago

When I ran the code, it said 'myfile' was not defined, but I fixed that and defined 'myfile' as local variables in doread() and dowrite().

Tim Pierce · Accepted Answer · 2015-11-07 02:28:10Z

The indentation here looks questionable:

def doread():
# open the mynumbers.txt and read all numbers from file using for loop
    myfile = open('mynumbers.txt', 'r')
#    line = myfile.readline()
# Read each line in the file and display
for line in myfile:
    print(line)
# Print each number as it is read and find the largest number.
    with open('mynumbers.txt', 'r') as myfile:
        largest = max(map(int, myfile))
        print('The largest number in the file is: ',largest)

Here you've defined this function:

def doread():
# open the mynumbers.txt and read all numbers from file using for loop
    myfile = open('mynumbers.txt', 'r')

and added this code at the top level of the program, when it looks like you meant to make it part of your doread function?

for line in myfile:
    print(line)
# Print each number as it is read and find the largest number.
    with open('mynumbers.txt', 'r') as myfile:
        largest = max(map(int, myfile))
        print('The largest number in the file is: ',largest)

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