python - Function works correctly only the first time it is called -

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• why can't call read() twice on open file? 7 answers

i have following function, second function count_forbid(a) can work 1 time. in example count right value of word not contain letter 'c', y return zero. means code can right first time , other time return zero:

import string fin = open('words.txt') def forbid_or_not(word,forb):     letter in word:         if letter in forb:             return false     return true  def count_forbid(a):     count = 0     line in fin:         word1 = line.strip()         if forbid_or_not(word1,a):             count += 1     return count  x = count_forbid('c') y = count_forbid('d') 

after iterate through file with:

    line in fin: 

it going reach end , trying re-iterate have no effect.

either change function use context manager re-opens file when function called:

def count_forbid(a):     count = 0     open('words.txt') fin:  # closes file automatically         line in fin:             word1 = line.strip()             if forbid_or_not(word1,a):                 count += 1     return count 

which preferred way of opening files in python.

or, add fin.seek(0) in between calls in order file point beginning:

x = count_forbid('c') fin.seek(0) y = count_forbid('d')