Binary file Handling in Python
A binary file stores the data in the same way as as stored in the memory. The .exe files, mp3 file, image files,
word documents are some of the examples
of binary files. We can’t read a binary file using a text editor.
Ø We can open some binary files in the normal text editor but we can’t read the content present inside the file, because the file will be encoded in the binary format
Ø There is no delimiter to end a line
Ø These files are easy to open and fast working
Important module in Binary file
1) 1 )Pickling
also know as Serialisation or flattening or marshalling.
:
In python, preserving data for future use is called
pickling.
Let’s understand in a
simple way. If a person who is speaking in German language and a person who is
speaking in the Hindi language in communication then it has meaning at all. In
this process, we need one person who knows both languages.
Pickling (Serialisation): module is doing
something exactly (conversion of python objects) in binary. This process is
known as pickling.
2)
2) Unpickling
or De-serialisation : The
inverse of the pickling process is known as unpickling.
The
pickle module consists of two main functions :
a) a) dump() b) load()
a)
dump() function : these function is used
during the pickling process. It convert python object for writing data in a
binary file.
Example-1 :
import pickle # Work with the pickle module
s1 = {'Rno':101,'Name':'Ankita'} # s1 and s2 dictionary to be stored in the binary file
s2 = {'Rno':102,'Name':'Jay'}
pickle.dump(s1,f) # write onto the file
pickle.dump(s2,f)
f.flush()
print("Data insert successfully...")
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Example-2 : # Insert information by users (Input method)
import pickle
stu = {}
f=open("Student.dat","wb")
ans = 'y'
while ans == 'y':
rno=int(input("Enter roll number "))
name=input("Enter Name ")
stu['Name']=name
ans = input("Want to enter more records?(Y / N)")
p.close()
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a)
load() function : these function is used
during the unpickling process. It is used to load data from a binary file
Example.
import pickle
stu = {} #declare empty dictionary to hold read records
f=open("Student.dat","rb") # read from the file
try: # try and except check the note
while True:
stu = pickle.load(f)
print(stu)
except EOFError:
f.close()
·
Note: Use try and except blocks:- Try and Except
statement is used to handle these errors within our code in Python. The try
block is used to check some code for errors,
EOFError: if End-Of-File is hit
without reading any data
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Example-1.: Searching data
import pickle
stu={}
found = False
f=open("Student.dat","rb")
Searchkeys = [101,102]
try:
print("Searching in file..")
while True:
stu=pickle.load(f)
if stu['Rno']in Searchkeys:
print(stu)
found = True
except EOFError:
if found == False:
print("NO such records found")
else:
print("Search sucessful..")
f.close()
Example-2.: Searching data by users (Input method)
import pickle
stu={}
found = False
rollno = int(input("Enter Roll No"))
f=open("Student.dat","rb")
try:
while True:
stu=pickle.load(f)
if stu['Rno'] == rollno:
print(stu)
found = True
except EOFError:
if found == False:
print("NO such records found")
else:
print("Search sucessful..")
f.close()
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First Page of File Handling Next: Data Structures
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