Python File Handlig

Here we discuss about how to handle text files using python. This function can be used to creating, reading, updating & deleting files.

Python File Open

open( ) - function is used to start file handling and it takes two parameters.

Structure

myfile = open("file name","mode")

Here we learn about three main modes in file handling ,
1) Write(w) 2) Append(a) 3) Read(r)

Python Write - w

We can creat a new file using this function, in the same location as the python file.

If the file already exist, data in it will be deleted and the new data will be replaced.

.write() Function

.write() - function is used to write something to the text file.

Example - 1

myfile = open("names.txt","w")
myfile.write("John")
myfile.write("\n paul")
myfile.write("\n Anji \n Hafsa") myfile.close()

\n - is used to creat a line break in python.

After execusion, the above code will creat the following file.

name.text

John
paul
Anji
Hafsa

Python append - a

We can creat a new file using this function, in the same location as the python file.

If the file already exist, the new data will be added to the end of the file.

.write() Fuction

.write() - function is used to write something to the text file.

Example - 2

myfile = open("names.txt","a")
myfile.write("Chadwick")
myfile.write("\n Steve")
myfile.close()

\n - is used to creat a line break in python.

After execusion, the above code will update the name.text file as follows.

name.text

John
paul
Anji
Hafsa
Chadwick
Steve

Python read - r

We can read exisiting files using this function, in the same location as the python file.

If the file doesn't exist, an error is raised.

.read() Function

.read() - function is used to read something from the text file.

Example - 3

myfile = open("names.txt","r")

#Assign the content in the file to a variable.

content = myfile.read()
print(content)
myfile.close()

After execusion, the above code will fetch the name.text file's content and prompt the following output.

Output

John
paul
Anji
Hafsa
Chadwick
Steve

.readline() function

When we need to fetch line by line from the name.txt file use the below method.

.readline() - function is used to read a single lline from the text file.

Example - 4

myfile = open("names.txt","r")

#Assign first line in the file to a variable.

content = myfile.readline()
print(content)
myfile.close()

After execusion, the above code will fetch the name.text files' first line and prompt the following output.

Output

John

We can use this method to fetch multiple lines as well as elements of lines

Example - 5

myfile = open("names.txt","r")

print(myfile.readline())
print(myfile.readline())
print(myfile.readline(2))
print(myfile.readline(3))
myfile.close()

After execusion, the above code will fetch the name.text files' lines and prompt the following output.

You can identify that how we can call the specific index of the line to segment it.

Output

John

paul

An
ji

Haf
sa

.readlines() function

.readlines() - function will assign the values the file to list.

Example - 6

myfile = open("names.txt","r")

result = myfile.readlines()
print(result)
myfile.close()

After execusion, the above code will fetch the name.text files' lines and prompt the following list.

Output

['John', 'paul', 'Anji', 'Hafsa', 'Chadwick', 'Steve']

Iteraring through lines of a file - for loop

.readlines() - function will assign the values the file to list.

Example - 7

myfile = open("names.txt","r")

for line in myfile:
print(line)
myfile.close()

After execusion, the above code will fetch the name.text files' lines and prompt the following output.

Output

John

paul

Anji

Hafsa

Chadwick

Steve

.split() method

.split() - method will allow us to split(divide) a sting and assign each item into a list.

Below code shows how to split a string from the "space".


                                line = "This is a random text"
                                list = line.split()
                                print(list)

Press Run to execute.

Below code shows how to split a string from the "=" mark. And extract items from the list.

contacts.txt

john = 07783425627
Anji = 07862897602
paul = 07673920172

Example - 8

myfile = open("contacts.txt","r")

for x in myfile:
name = x.split("=")[0]
print(name)
myfile.close()

After execusion, the above code will fetch only the names of the contact holders from contacts.txt file and prompt the following output.

Output

John
Anji
paul

Sequential Search

Search the names the in file to get the number as an output.

Example - 9

myfile = open("contacts.txt","r")
searchkey = input("search name -")
status - "No contacts found"

for x in myfile:
name = x.split("=")[0]
if (searchkey == name):

print(name)

status = "Above contacts are found"

print(status)
myfile.close()

Example output

Output

Search name - john
john = 07783425627
Above contacts are found.

#Next entry

Search name - hafsa
No contacts found