Python在文本文件中找不到第二行

Question

I have a problem. When I search for the ID, the information appears only on the first line of the textfile. But when search for another ID that isn't on the first line, can't find it

import random
def create_sup():
    with open("supplier.txt","a+") as file:
        sup_name = input("Enter New Supplier's Name : ")
        sup_idgen = random.randint(0,9999)
        sup_id = sup_idgen
        print("Supllier ID : ",sup_id)
        sup_city = input("Enter New Supplier's City : ")
        sup_contact = int(input("Enter New Supplier's Contact Number : "))
        sup_email = input("Enter New Supplier's Email : ")
        columnsup = [sup_name,sup_id,sup_city,sup_contact,sup_email]
        file.write(str(columnsup)+"\n")


def s_searchbyid():
    with open("supplier.txt","r") as file:
        data = file.readline().split("\n")
        id = input("Enter Supplier ID : ")
        for line in data:
            if id in line:
                print(line)

Answer 1

The readline method reads only one line. In your case you read one line and split it based on newline '\\n' (there is none) so what you eventually end up with is a one element list.

Use data = file.read().split("\\n")

Answer 2

I made some changes to your program:

import random


def create_sup():
    sup_name = input("Enter New Supplier's Name: ")
    sup_idgen = random.randint(0, 9999)
    sup_id = sup_idgen
    print("Supplier ID : ", sup_id)
    sup_city = input("Enter New Supplier's City: ")
    sup_contact = int(input("Enter New Supplier's Contact Number: "))
    sup_email = input("Enter New Supplier's Email: ")
    # Only open file when necessary.
    with open('supplier.txt', 'a') as file_1:
        file_1.write(f'{sup_name}, {sup_id}, {sup_city}, {sup_contact}, {sup_email}\n')


def s_searchbyid():
    sup_id = input("Enter Supplier ID : ")
    # Only open file when necessary.
    with open('supplier.txt', 'r') as file_1:
        # Iterate over the lines of the file. Yes, it's that simple!
        for line in file_1:
            if sup_id in line:
                print(line)

Of course, this code does not have the problem you were facing. There are a few comments to explain the changes.

Let me know if you have any questions or if something is unclear :)