IO_ReadWriteFile_python

Open Read Write File

open syntax:　

open( file, mode, encoding="utf-8")

mode 字串	說明
r	Read only 讀取模式 ( 預設 )
r+	Read and write
w	Write only 寫入模式，檔案若存在，會清空內容再寫入； 若檔案不存在，則建立新檔開啟寫入
w+	write+read
a	Append only 附加模式，若檔案存在，則寫入內容會附加至檔 案尾端
a+	Append and Read (‘a+’)

Read

讀取方法	描述
read( )	一次讀取檔案所有的內容，回傳為字串
readline( )	只讀取一行內容
readlines( )	將所有檔案內容，每行讀入回傳為串列

fileObj = open("路徑檔名" , "r", encoding="utf-8") 
content = fileObj.read( ) 
fileObj.close( )

Write

fileObj = open("路徑檔名" , "w", encoding="utf-8")
fileObj.write(輸出資料)
fileObj.close( ) 

Example

Ex1. read file and print

Note: Avoid reading with new line
line = line.strip()
or
print(line,end='')

with open('test.txt') as f,open('out.txt', 'w') as f_out:
    for line in f:
        line = line.strip()
        print(line)

Ex2: Read a file from text file and write to another file

with open('test.txt') as f,open('out.txt', 'w') as f_out:
    for line in f:
        line = line.strip()
        #print(line)
        f_out.write('{}\n'.format(line))

ex3 write file

with open ('video_title_url.txt', 'w', encoding='UTF-8') as f_out:
    for line_index in downloadlink:
        line = line_index.strip()
        f_out.write('{}\n'.format(line))   
    print("end")