Python Tutorial | Python Data File Handling 4

with statement

Apart from using open() or file() function for the creation of a file, “with statement” can also be used for the same purpose. We can use this statement to group file operations within a block. Using “with” ensures that all the resources allocated to the file object get deallocated automatically once we stop using the file. In the case of exceptions also, we are not required to close the file explicitly using “with” statement.

syntax:
with open(filename) as fileobject:
              statements
              statements

Example of “with” statement:

Python program to write contents into a file named “abc.txt”

#to write contents in the file
with open("abc.txt","w") as f:
    f.write("hello how are you\n")
    f.write("welcome to python file handling\n")
    f.write("end of the file\n")
#close the file
f.close()

Now to read the contents of the above created file and display them.

#to read the contents of the file
f=open("abc.txt","r")
data=f.readlines()
for i in data:
    print(i,end='')
    
#close the file
f.close()

Output:

hello how are you
welcome to python file handling
end of the file
>>> 

Appending data to a file

Append means “to add to”; so if we want to add more data to a file that already has some data in it, we have to open the file in append mode. In such a case, we use access mode “a” which means “open for writing, and if it exists, then append data to the end of the file”.

In Python, we can use the “a” mode to open an output file in append mode. this means that:

* if the file already exists, it will not be erased. if the file does not exist, it will be created.

* When data is written to the file, it will be written at the end of the file’s current contents.

Example of append mode:

Python program to write contents into a file named “abc.txt”

#to write contents in the file
with open("abc.txt","w") as f:
    f.write("hello how are you\n")
    f.write("welcome to python file handling\n")
    f.write("end of the file\n")
#close the file
f.close()
#to write contents in the file in append mode
with open("abc.txt","a") as f:
    f.write("This is new data line 1\n")
    f.write("This is new data line 2\n")
    f.write("end of the file\n")
#close the file
f.close()

Now to read the contents of the above created file and display them.

#to read the contents of the file
f=open("abc.txt","r")
data=f.readlines()
for i in data:
    print(i,end='')
    
#close the file
f.close()

Output:

hello how are you
welcome to python file handling
end of the file
This is new data line 1
This is new data line 2
end of the file
>>> 

Python Basic Programming Tutorial

Python Introduction     Getting started in Python Programming      Python propgramming fundamentals     Python Operators    Python If Condition     Python for loop    Python range construct      Python While loop    break and continue statements     Different looping techniques     Python List     Python String     Python Functions    Python Inbuilt Functions     Python Recursion     Using Python Library     Python Tuples     Python Dictionary     Python Sets     Python Strings     Python Exception Handling     Python Data File Handling

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