Open a File on the Server
Assume we have the following file, located in the same folder as Python:
demofile.txtHello! Welcome to demofile.txt
This file is for testing purposes.
Good Luck!
To open the file, use the built-in open() function.
The open() function returns a file object, which has a read() method for reading the content of the file:
Example
f = open(“demofile.txt”, “r”)
print(f.read())
Output:
C:\Users\My Name>python demo_file_open.py
Hello! Welcome to demofile.txt
This file is for testing purposes.
Good Luck!
If the file is located in a different location, you will have to specify the file path, like this:
Example
Open a file on a different location:f = open(“D:\\myfiles\welcome.txt”, “r”)
print(f.read())
Output:
C:\Users\My Name>python demo_file_open_d.py
Welcome to this text file!
This file is located in a folder named “myfiles”, on the D drive.
Good Luck!
Read Only Parts of the File
By default the read() method returns the whole text, but you can also specify how many characters you want to return:
Example
Return the 5 first characters of the file:f = open(“demofile.txt”, “r”)
print(f.read(5))
Output:
C:\Users\My Name>python demo_file_open2.py
Hello
Read Lines
You can return one line by using the readline() method:
Example
Read one line of the file:f = open(“demofile.txt”, “r”)
print(f.readline())
Output:
C:\Users\My Name>python demo_file_readline.py
Hello! Welcome to demofile.txt
By calling readline() two times, you can read the two first lines:
Example
Read two lines of the file:f = open(“demofile.txt”, “r”)
print(f.readline())
print(f.readline())
Output:
C:\Users\My Name>python demo_file_readline2.py
Hello! Welcome to demofile.txt
This file is for testing purposes.
By looping through the lines of the file, you can read the whole file, line by line:
Example
Loop through the file line by line:f = open(“demofile.txt”, “r”)
for x in f:
print(x)
Output:
C:\Users\My Name>python demo_file_readline3.py
Hello! Welcome to demofile.txt
This file is for testing purposes.
Good Luck!
Close Files
It is a good practice to always close the file when you are done with it.
Example
Close the file when you are finish with it:f = open(“demofile.txt”, “r”)
print(f.readline())
f.close()
Output:
C:\Users\My Name>python demo_file_close.py
Hello! Welcome to demofile.txt
Note: You should always close your files, in some cases, due to buffering, changes made to a file may not show until you close the file.