How To Open a File in Python

Python provides inbuilt functions for handling files, i.e., creating, reading, writing, etc. Python handles two types of files. They are Text and binary files.

• Text file – In a text file, each line of Text is terminated by the end of Line (EOL) operator, a special character ‘\n’ in Python by default.
• Binary file – The binary file contains the binary data of forms 0’s and 1’s. Machines understand binary language.

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How To Open a File in Python

The open() method in Python opens a file in a specified path and mode. Below is the syntax of the open() method to open a file –

open(‘file_name’,’Access_mode’)

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Different access modes to open a file in Python

1. file_name

Specifies the name of the file to open. If the Python script is not present in the same directory/folder of the file which needs to be opened, then the file’s path also needs to be specified along with the file name.

2. Access_mode

Specifies the access mode of the opened file. Below listed are the available access modes.

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3. Read only

It opens the specified file in read mode. This access mode is represented as “r.” If any access mode is not specified in the open() method, then the file will be opened in read mode by default. If the file specified is not present, it throws an error.

4. Write only

It opens the specified file in write mode. This access mode is represented as “w.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, it truncates the data and overwrites it with new data.

5. Append only

It opens the specified file in write mode. This access mode is represented.” as “a.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, then it appends the new data from the end of already existing data.

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6. Read and write

It opens the specified file in read and writes mode. This access mode is represented as “r+.” If the file specified is not present, then it throws the error. If the specified file is already present, it truncates the data and overwrites it with new data.

7. Write and read

It opens the specified file in write and read mode. This access mode is represented as “w+.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, it truncates the data and overwrites it with new data.

8. Append and read

It opens the specified file in write and read mode. This access mode is represented as “a+.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, then it appends the new data from the end of already existing data.

9. Read only in binary format

It opens the specified file for reading in binary format. This access mode is represented as “rb.” If any access mode is not specified in the open() method, then the file will be opened in read mode by default. If the file specified is not present, it throws an error.

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10. Write only in binary format

It opens the specified file for writing in binary format. This access mode is represented as “wb.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, it truncates the data and overwrites it with new data.

11. Append only in binary format

It opens the specified file for writing in binary format. This access mode is represented as “ab.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, then it appends the new data from the end of already existing data.

12. Read and write in binary format

It opens the specified file for reading and writing in binary format. This access mode is represented as “rb+.” If the file specified is not present, then it throws the error. If the specified file is already present, it truncates the data and overwrites it with new data.

13. Write and read in binary format

It opens the specified file for reading and writing in binary format. This access mode is represented as “wb+.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, it truncates the data and overwrites it with new data.

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14. Append and read in binary format

It opens the specified file for reading and writing in binary format. This access mode is represented as “ab+.” If the specified file is not present, it creates a file with the specified name. If the specified file is already present, then it appends the new data from the end of already existing data.

Here is a simple program that uses the open() method to open a file with a particular access mode.

Code:

# opening a file to add data to a file which already has some data and also to read the data.
fileObj = open( “demo.txt” , “a+”)

# append new data
fileObj.write(“ - Himanshu”)
# print the data in the file
print(fileObj.read())

# closing the file
fileObj.close()

File demo.txt before execution of code.

File demo.txt after execution of code.

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Opening a file in read mode

To open a file in read mode in Python, you can use the following code:

f = open("filename.txt", "r")

This will open the file filename.txt in read mode and assign the file object to the variable f.

You can then read the file’s contents using f.read() or f.readline().

Here is an example of how you can use f.read() to read the entire contents of the file.

f = open("filename.txt", "r")
contents = f.read()
print(contents)
f.close()

Be sure to close the file when you are done with it using f.close(). This will free up system resources associated with the file.

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Summary

Using the open() function, we opened a demo.txt file in append and read mode by passing the “a+” access mode. So it opens the specified file in write and read mode. Any data we write into the file using the script will be later appended to the data if already present. The write() & read() methods help to write any data into the file and read the data present in the file.

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