Files :
To
store data in permanently:
1. Files
2. Database
#example
program on without using files:
a=input("enter any string ");
print(a)
Above
program only process the data, but it will not store the data permanently in
the hard disk. Because it stores in RAM (Random Access memory).
To store
data we have to go for the following options:
1. Files
2. Using data base
Files:
#creating
a file with name rfile.txt
f=open("rfile.txt","w")
a=input("enter any string:")
f.write(a)
f.close()
File definition:
File
is a collection of related information which stores in our hard disk permanently.
Advantages:
1. When the data is stored in a
file, it is stored in the memory permanently.
2.
Updating becomes easy. For example we add or delete new data to the
existing file, we can delete unnecessary data from the file.
3.
This file can be sharable to other modules or other programs.
4. Huge amount of data can be
stored in a file.
Types of Files:
1. Text files
2. Binary Files
Test
file store the data in the form of characters.
Binary
Files stores the data in the form of bytes.
i.e a group of 8 bits.
It
can store text file, image file, audio and video.
We
have to follow some steps to handling the files:
1. Open a file
Example: f=open("rfile.txt","w")
2. Read /Write files
f.write(a)
3.
Closing the file
Example: f.close()
Example:
2:
#Reading a file from already existing
#Reading
a file from already existing
#step1
f=open("rfile.txt","r")
#step2:
a=f.read(9)
print(a)
print(type(a))
#Step
3:
f.close()
"""
Hello
I'm
<class
'str'>
"""
Example 3: using readlin() function
#Ex3:
Reading a file from already existing
#step1
f=open("rfile.txt","r")
#step2:
##a=f.read(9)
a=f.readline()
print(a)
print(type(a))
#Step
3:
f.close()
"""
Hello
I'm rajendra
<class
'str'>
"""
File
mode
|
Meaning
|
w
|
To
write the data into file. If already exists the file, previous data is
deleted with ‘w’ mode.
|
r
|
To
read the data from the file. Actually fp (file pointer) points to the beginning
of the file. Where fp is a variable identifier. It acts as a just like a pointer.
|
w+
|
To
write and read the data from the file. Previous data is deleted.
|
a
|
Appending
mode. Adding the new data to the existing file at the end of the existing file.
Here f or fp points at the end of the file. If file does’nt exist, it creates
a new file for writing the data
|
r+
|
To
read and write the data into a file. Previous data is not deleted
|
a+
|
To
append and read data of a file.
|
x
|
Exclusive
mode. If already exits one file, it will not create the file.
|
#Ex3: By using looping to read the data entire
#step1: open the file rifle.txt in read mode.
f=open("rfile.txt","r")
#step2:execute the loop to read entire txt file
#a=f.readline()
for i in f:
print(i)
#Step 3:
f.close()
"""
Hello
I'm rajendra
I'm
from Vijayawada
Python...
"""
Closing a file: f.close()
Syntax:
variable.close()
A
file which opened should closed using close() method. If a file is opened but
we forgot to close the file, that file may be corrupted or deleted.
Writing
the file to the existing file:
##Example
program on appending the file
f=open("rfile.txt","a")
#appending
the data to the file
f.write("we
are going to write and give viva for python")
#closing
the opened file
f.close()
once
you execute the above code, go to your directory check the file.
f=open("pyt.txt","x")
print(f)
if f:
print("file created successfully
")
"""
It
leads to error if already exists.
Otherwise
creates new file
"""
Next: Files part 2
Previous:
Exceptions:
https://youtu.be/TeVaBIo-WQo