Python
Python List count() with EXAMPLES
Python count The count() is a built-in function in Python. It will return the total count of a...
In Python, there is no need for importing external library to read and write files. Python provides an inbuilt function for creating, writing, and reading files.
In this file handling in Python tutorial, we will learn:
To open a file, you need to use the built-in open
function. The Python open file function returns a file object that contains methods and attributes to perform various operations for opening files in Python.
Syntax of Python open file function
file_object = open("filename", "mode")
Here,
More details of these modes are explained below
With Python Write to File, you can create a .text files (guru99.txt) by using the code, we have demonstrated here:
Step 1)
f= open("guru99.txt","w+")
Step 2)
for i in range(10): f.write("This is line %d\r\n" % (i+1))
Step 3)
f.close()
Here is the result after code execution for Python create file
When you click on your text file in our case "guru99.txt" it will look something like this
You can also append/add a new text to the already existing file or a new file.
Step 1)
f=open("guru99.txt", "a+")
Once again if you could see a plus sign in the code, it indicates that it will create a new file if it does not exist. But in our case we already have the file, so we are not required to create a new file for Python append to file operation.
Step 2)
for i in range(2): f.write("Appended line %d\r\n" % (i+1))
This will write data into the file in append mode.
You can see the output in "guru99.txt" file. The output of the code is that earlier file is appended with new data by Python append to file operation.
Step 1) Open the file in Read mode
f=open("guru99.txt", "r")
Step 2) We use the mode function in the code to check that the file is in open mode. If yes, we proceed ahead
if f.mode == 'r':
Step 3) Use f.read to read file data and store it in variable content for reading files in Python
contents =f.read()
Step 4) Print contents for Python read text file
Here is the output of the Python read file example:
You can also read your .txt file line by line if your data is too big to read. readlines() code will segregate your data in easy to read mode.
When you run the code (f1=f.readlines()) to read file line by line in Python, it will separate each line and present the file in a readable format. In our case the line is short and readable, the output will look similar to the read mode. But if there is a complex data file which is not readable, this piece of code could be useful.
Following are the various File Modes in Python:
Mode | Description |
---|---|
'r' | This is the default mode. It Opens file for reading. |
'w' | This Mode Opens file for writing. If file does not exist, it creates a new file. If file exists it truncates the file. |
'x' | Creates a new file. If file already exists, the operation fails. |
'a' | Open file in append mode. If file does not exist, it creates a new file. |
't' | This is the default mode. It opens in text mode. |
'b' | This opens in binary mode. |
'+' | This will open a file for reading and writing (updating) |
Here is the complete code for Python print() to File Example
Python 2 Example
def main(): f= open("guru99.txt","w+") #f=open("guru99.txt","a+") for i in range(10): f.write("This is line %d\r\n" % (i+1)) f.close() #Open the file back and read the contents #f=open("guru99.txt", "r") # if f.mode == 'r': # contents =f.read() # print contents #or, readlines reads the individual line into a list #fl =f.readlines() #for x in fl: #print x if __name__== "__main__": main()
Python 3 Example
Below is another Python print() to File Example:
def main(): f= open("guru99.txt","w+") #f=open("guru99.txt","a+") for i in range(10): f.write("This is line %d\r\n" % (i+1)) f.close() #Open the file back and read the contents #f=open("guru99.txt", "r") #if f.mode == 'r': # contents =f.read() # print (contents) #or, readlines reads the individual line into a list #fl =f.readlines() #for x in fl: #print(x) if __name__== "__main__": main()
Summary
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