Python File Input/Output

In file I/O, we perform operations (open, close, read, write, create, delete, etc.) on a file.

Open File

To open a file, use the `open()` function. The syntax for opening a file is:

Syntax 1
variable_name = open("file_name", "opening_mode")
Syntax 2
with open("file_name", "opening_mode") as variable_name:
    # statements

Here, the `file_name` refers to the file you want to open.

Modes of Opening File

The table below shows the modes for opening a file:

Modes

Meaning

r

Opens a file in read mode. Error occurs if the file does not exist.

a

Opens a file in append mode. Creates the file if it does not exist.

w

Opens a file in write mode. Creates the file if it does not exist.

x

Creates a new file. Error occurs if the file already exists.

t

Opens a file in text mode.

b

Opens a file in binary mode.

Close File

After performing operations, close the file using the close() function.

Syntax
variable_name.close()
Read File

read() and readline() functions are used to read a file.

Syntax of read() Function
variable_name.read()
Example 1

Suppose the file `eb.py` contains a program to add two numbers:

file_var = open("eb.py", "r")
print(file_var.read()) 
Output
a = 10
b = 20
print("sum:", a + b)
Example 2

Suppose the file `eb.py` contains a program, and you want to read a fixed number of characters:

file_var = open("eb.py", "r")
print(file_var.read(10)) 
Output
a = 10
b = 20

It reads the first 10 characters, including newlines and whitespaces.

readline() reads one line of the file at a time.

Syntax of readline() Function
variable_name.readline()
Example 1

Suppose the file `eb.py` contains a program to add two numbers:

file_var = open("eb.py", "r")
print(file_var.readline()) 
Output
a = 10