How to search txt file from python using while loop

Question

I have this code:

b = str(raw_input('please enter a book '))
searchfile = open("txt.txt", "r")
for line in searchfile:
    if b in line:
        print line
        break
else:
    print 'Please try again'

This works for what I want to do, but I was wanting to improve on it by repeating the loop if it goes to the else statement. I have tried running it through a while loop but then it says 'line' is not defined, any help would be appreciated.

possible duplicate of [Python: read file line by line into array](http://stackoverflow.com/questions/3277503/python-read-file-line-by-line-into-array) — Celeo, Apr 28 '15 at 17:30
Okay i thought it was something like that, thanks. Basically if a title of the book is not in the txt document i want to be able for it to repeat the question to give the user another chance to input a book title. — toby, Apr 28 '15 at 17:34
In that case just put the whole thing in a `while` loop guarded by a `bool` variable, and when you find an instance of the book title in the loop set the variable so that you exit the loop. — malfunctioning, Apr 28 '15 at 17:37
Yes it is spaced 4 times, but it reads through each book title printing not available for each one until it comes to the book that meets the search — toby, Apr 28 '15 at 17:39
There is no such statement as `while line in searchfile:`, although there is `While True: for line...` — Ben Morris, Apr 28 '15 at 17:41

score 2 · Accepted Answer · answered Apr 28 '15 at 17:39

Assuming you want to repeat the search continually until something is found, you can just enclose the search in a while loop guarded by a flag variable:

with open("txt.txt") as searchfile:
    found = False
    while not found:
        b=str(raw_input('please enter a book '))
        if b == '':
            break  # allow the search-loop to quit on no input
        for line in searchfile:
            if b in line:
                print line
                found = True
                break
        else:
            print 'Please try again'
            searchfile.seek(0)  # reset file to the beginning for next search

score 0 · Answer 2 · answered Apr 28 '15 at 17:39

Try this:

searchfile = open("txt.txt", "r")
content = searchfile.readlines()
found = False

while not found:
    b = raw_input('Please enter a book ')
    for line in content:
        if b in line:
            print line
            found = True
            break
    else:
        print 'Please try again'

searchfile.close()

You load the content in a list and use a boolean flag to control if you already found the book in the file. When you find it, you're done and can close the file.

How to search txt file from python using while loop

2 Answers2