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1filehandling.py
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1filehandling.py
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import os
rl = 20
#1st function to write the data
def writeData():
f = open("cities.bin","ab")
n = int(input("How many cities: "))
for i in range(n):
city = input("Enter city name: ")
cl = len(city)
city = city + (rl - cl) * " "
f.write(city.encode())
f.close()
def readData():
f = open("cities.bin","rb")
city = f.read()
print(city.decode())
f.close()
def searchByPosition(pos):
f = open("cities.bin","rb")
f.seek((pos-1)*rl,0)
city = f.read(rl)
print(city.decode())
f.close()
def searchByCity(scity):
f = open("cities.bin","rb")
pos = 0
filesize = os.path.getsize("cities.bin")
n = int(filesize/rl)
flag = 0
for i in range(n):
f.seek(pos)
city = f.read(rl)
if city.decode().strip().lower() == scity.lower():
flag = 1
break
pos += rl
f.close()
return flag,(i+1)
def updateCity(city):
flag,pos = searchByCity(city)
if flag == 0:
print("city dosen't Exist")
else:
#ncity = input("Enter new city :")
#print(pos)
f = open("cities.bin","r+b")
f.seek((pos-1)*rl)
ncity = input("Enter new city name : ")
ncl = len(ncity)
ncity = ncity + (rl - ncl) * " "
f.write(ncity.encode())
f.close()
def deleteCity(ncity):
flag,pos = searchByCity(ncity)
if flag == 0:
print("City doesn't exist")
else:
filesize = os.path.getsize("cities.bin")
n = int(filesize/rl)
f1 = open("cities.bin","rb")
f2 = open("ncity.bin","wb")
for i in range(n):
city = f1.read(rl)
if city.decode().strip().lower() != ncity.lower():
f2.write(city)
f1.close()
f2.close()
os.remove("cities.bin")
os.rename("ncity.bin","cities.bin")
while True:
print("1.write data to file")
print("2.Read data to file")
print("3.Search by position")
print("4.Search by city")
print("5.Update city")
print("6.delete city")
print("7.Exit")
choice = int(input("Enter your choice: "))
if choice == 1:
writeData()
elif choice == 2:
readData()
elif choice == 3:
pos = int(input("Enter Position : "))
searchByPosition(pos)
elif choice == 4:
city = input("enter city: ")
flag,position = searchByCity(city)
if flag == 0:
print("city not found...")
else:
print("city found at position",position)
elif choice == 5:
city = input("Enter which city you want to update: ")
updateCity(city)
elif choice == 6:
city = input("Enter which city you want to delete:")
deleteCity(city)
elif choice == 7:
break
# random access - binary file handling - all operations
reclen = 20
import os
def insertbyname():
pos = int(input("enter position : "))
country = input("Enter country name to be inserted : ")
with open("countries.bin","rb") as f1, open("countries1.bin","wb") as f2:
data = f1.read(reclen * (pos-1))
f2.write(data)
n = len(country)
country = country + (reclen-n) * " "
country = country.encode()
f2.write(country)
data = f1.read()
f2.write(data)
os.remove("countries.bin")
os.rename("countries1.bin","countries.bin")
print("Record inserted successfully")
def deletebyname():
cnm = input("Enter country name to delete: ")
pos = searchbyname(cnm)
if pos==-1:
print("Reocrd can not be updated as it is not there in file")
else:
filesize = os.path.getsize("countries.bin")
nor = int(filesize/reclen)
with open("countries.bin","rb") as f1, open("countries1.bin","wb") as f2:
pos = 0
flag=0
for i in range(nor):
f1.seek(pos)
country = f1.read(20)
if country.decode().strip().lower()!=cnm.lower():
f2.write(country)
pos+=reclen
os.remove("countries.bin")
os.rename("countries1.bin","countries.bin")
print("Record deleted successfully")
def updatebyname():
cnm = input("Enter country name to update: ")
pos = searchbyname(cnm)
if pos==-1:
print("Reocrd can not be updated as it is not there in file")
else:
with open("countries.bin","r+b") as f:
f.seek(pos)
ncnm = input("Provide new name : ")
n = len(ncnm)
ncnm = ncnm + (reclen-n) * " "
ncnm = ncnm.encode()
f.write(ncnm)
def writedata():
n = int(input("How many countries?: "))
with open("countries.bin","wb") as f:
for i in range(n):
country = input("Enter country name : ")
n = len(country)
country = country + (reclen-n) * " "
country = country.encode()
f.write(country)
# f.write(country+((reclen-len(country)) * " "))
def readalldata():
with open("countries.bin","rb") as f:
data = f.read()
print(data.decode())
def searchbypos():
n = int(input("Enter position: "))
with open("countries.bin","rb") as f:
f.seek(reclen * (n-1))
country = f.read(20)
print(country.decode())
def searchbyname(cnm):
with open("countries.bin","rb") as f:
filesize = os.path.getsize("countries.bin")
nor = int(filesize/reclen)
pos = 0
flag=0
for i in range(nor):
f.seek(pos)
country = f.read(20)
if country.decode().strip().lower()==cnm.lower():
flag=1
print("Record found at : ",i+1)
break
pos+=reclen
if flag==0:
print("Record not found")
pos=-1
return pos
while True:
print("1) Write data to file")
print("2) Read all data from file")
print("3) Search by position")
print("4) Search by name")
print("5) Update country")
print("6) Delete country")
print("7) Insert country")
print("9) Exit")
choice = int(input("Enter your choice : "))
if choice==1:
writedata()
elif choice==2:
readalldata()
elif choice==3:
searchbypos()
elif choice==4:
cnm = input("Enter country name : ")
searchbyname(cnm)
elif choice==5:
updatebyname()
elif choice==6:
deletebyname()
elif choice==7:
insertbyname()
elif choice==9:
break
# to append data to an existing file and displaying the entire file.
# f = open("message.txt","a+")
# while True:
# data = input()
# if data=="*":
# break
# else:
# f.write(data+"\n")
# f.seek(5,0)
# data = f.read()
# print(data)
# f.close()