如何从包含特定短语的文本文件中打印每一行

Question

I have to write a function which can search a txt file for a phrase then print every line that contains the phrase.

def find_phrase(filename,phrase):
    for line in open(filename):
        if phrase in line: 
            print line,

That is what I have at the moment and it only prints the first instance.

Answer 1

I have tried your code with a sample script, which goes like this

#sample.py

import sys
print "testing sample"
sys.exit() 

when i run your script,

find_phrase('sample.py','sys')

It prints,

import sys
sys.exit(). 

If this is not your intended output, please share the file you are using.

Answer 2

Below is the pythonic approach. The with statement will safely open the file and handle closing the file when it is done. You can also open multiple files with the "with" statement. How to open a file using the open with statement

def print_found_lines(filename, phrase):
    """Print the lines in the file that contains the given phrase."""
    with open(filename, "r") as file:
        for line in file:
            if phrase in line:
                print(line.replace("\n", ""))
    # end with (closes file automatically)
# end print_found_lines