Hướng dẫn python find string in text file and print line - python tìm chuỗi trong tệp văn bản và dòng in

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Đọc

Example:

string = "GEEK FOR GEEKS"

Input: "FOR" 
Output: Yes, FOR is present in the given string.

Bàn luận

myfile.txt

Trong bài viết này, chúng ta sẽ xem cách tìm kiếm một chuỗi trong các tệp văn bản bằng Python

Tệp văn bản để trình diễn:

Python3

with open

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

Phương pháp 1: & nbsp; Tìm chỉ mục của chuỗi trong tệp văn bản bằng readline []

Trong phương thức này, chúng tôi đang sử dụng hàm readline [] và kiểm tra hàm find [], phương thức này trả về -1 nếu không tìm thấy giá trị và nếu thấy nó trả về 0.

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

string does not exist

string does not exist

string does not exist

string does not exist

string does not exist in a file

string does not exist in a file

string does not exist in a file

string does not exist in a file

string does not exist in a file

def lines_that_equal[line_to_match, fp]:
    return [line for line in fp if line == line_to_match]

def lines_that_contain[string, fp]:
    return [line for line in fp if string in line]

def lines_that_start_with[string, fp]:
    return [line for line in fp if line.startswith[string]]

def lines_that_end_with[string, fp]:
    return [line for line in fp if line.endswith[string]]

string does not exist in a file

string does not exist in a file

def lines_that_equal[line_to_match, fp]:
    return [line for line in fp if line == line_to_match]

def lines_that_contain[string, fp]:
    return [line for line in fp if string in line]

def lines_that_start_with[string, fp]:
    return [line for line in fp if line.startswith[string]]

def lines_that_end_with[string, fp]:
    return [line for line in fp if line.endswith[string]]

def lines_that_equal[line_to_match, fp]:
    return [line for line in fp if line == line_to_match]

def lines_that_contain[string, fp]:
    return [line for line in fp if string in line]

def lines_that_start_with[string, fp]:
    return [line for line in fp if line.startswith[string]]

def lines_that_end_with[string, fp]:
    return [line for line in fp if line.endswith[string]]

Output:

-1
-1
0
string exists in file
line Number: 4
-1
-1

string does not exist

4

string does not exist

5

-1
-1
0
string exists in file
line Number: 4
-1
-1

7

string does not exist

7

string does not exist

string does not exist

string does not exist in a file

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

string does not exist in a file

string does not exist in a file

Python3

with open

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

def generate_lines_that_equal[string, fp]:
    for line in fp:
        if line == string:
            yield line

def generate_lines_that_equal[string, fp]:
    for line in fp:
        if line == string:
            yield line

string does not exist in a file

Phương pháp 2: Tìm chuỗi trong tệp văn bản bằng Read []

Chúng tôi sẽ tìm kiếm chuỗi từng dòng nếu chuỗi được tìm thấy thì chúng tôi sẽ in số chuỗi và số đó bằng hàm read [].

string does not exist in a file

string does not exist in a file

string does not exist in a file

with open["file.txt", "r"] as fp:
    for line in lines_that_equal["my_string", fp]:
        print line

string does not exist in a file

string does not exist

with open["file.txt", "r"] as fp:
    for line in generate_lines_that_equal["my_string", fp]:
        print line

string does not exist in a file

string does not exist in a file

string does not exist in a file

string does not exist in a file

with open["file.txt", "r"] as fp:
    for line in generate_lines_that_equal["my_string", fp]:
        print line

string does not exist in a file

Output:

string does not exist

string does not exist

4

def generate_lines_that_equal[string, fp]:
    for line in fp:
        if line == string:
            yield line

55

-1
-1
0
string exists in file
line Number: 4
-1
-1

7

def generate_lines_that_equal[string, fp]:
    for line in fp:
        if line == string:
            yield line

2

def generate_lines_that_equal[string, fp]:
    for line in fp:
        if line == string:
            yield line

8Search for a String in Text Files using enumerate[]

string does not exist

string does not exist

with open["file.txt", "r"] as fp:
    for line in lines_that_equal["my_string", fp]:
        print line

string does not exist

with open["file.txt", "r"] as fp:
    for line in lines_that_equal["my_string", fp]:
        print line

Python3

with open

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

Phương pháp 3: Tìm kiếm một chuỗi trong các tệp văn bản bằng cách sử dụng Enumerate []

Chúng tôi chỉ tìm thấy chuỗi có mặt trong tệp hoặc không sử dụng Enumerate [] trong Python.

-1
-1
0
string exists in file
line Number: 4
-1
-1

string does not exist

string does not exist

string does not exist in a file

-1
-1
0
string exists in file
line Number: 4
-1
-1

-1
-1
0
string exists in file
line Number: 4
-1
-1

string does not exist in a file

string does not exist in a file

-1
-1
0
string exists in file
line Number: 4
-1
-1

string does not exist in a file

Output:

string does not exist in a file