如何在 .txt 文件中搜索字符串并打印字符串所在的行？ （Python）

Question

Question above. I'm trying to create a contact book inside of the console in Python 3, and i'm trying to implement a "search" command, but everything i've tried didn't work. I didn't find anything helpful on the internet either.

f = open("C:/Users/Yonas/Documents/PythonProject.txt", "a")
entry = input()
i = 0

def add():
    print("Please type in the name of the person you want to add.")
    in2 = input()
    f.write(in2 + " | ")

    print("Please type in the location of the person you want to add.")
    in3 = input()
    f.write(in3 + " | ")

    print("Please type in some additional information.")
    in4 = input()
    f.write(in4 + "\n")

def search():
    line_number = 0
    print("Please type in the name of the person you're looking for.")
    inSearch = input()
    list_of_results = list(f)
    
    # The code should be here

if entry.startswith("add"):
    add()

if entry.startswith("search"):
    search()

Hope you understand my problem.

Answer 1

A slightly reworked version of your original snippet:

contact_book_path = "collection.txt"


def add():
    with open(contact_book_path, "a") as contact_book_fp:
        contact = ""

        name = input("Please type in the name of the person you want to add.\n")
        contact += name + " | "

        location = input("Please type in the location of the person you want to add.\n")
        contact += location + " | "

        info = input("Please type in some additional information.\n")
        contact += info + "\n"

        contact_book_fp.write(contact)


def search():

    with open(contact_book_path, "r") as contact_book_fp:
        name_search = input(
            "Please type in the name of the person you're looking for.\n"
        )

        for line_no, contact in enumerate(contact_book_fp.readlines()):
            name, location, info = contact.split(" | ")

            if name == name_search:
                print("Your contact was found at line " + str(line_no))
                return

        print("Your contact was not found! :(")


entry = input("What kind of operation would you like to do (add/search)?\n")
if entry.startswith("add"):
    add()

if entry.startswith("search"):
    search()

Instead of having the file open in and in append mode, I'd suggest you to open it for the right operation when you really need it. So for appending in add and for reading in search .

In the search function after opening the file and asking for the name to search for, you can use the standard file.readlines() method to iterate through the lines in a file. Also I used the enumerate function to get a running index together with a line, and I can use it as the line number later on.

Having put all these together, you can basically enhance the lookup logic any way you want.