File Handling In Python-

Ex-

class Test:
    file = None
    def main():
        try:
            Test.file = open("./test.txt") #builin module(We are assuming that you have test.txt in same folder)
            print("****Read the content at an instance****")
            content = Test.file.read()
            print(content)
            print("****Read the content char by char****")
            for ch in content:
                print(ch, end='')
        except Exception as ex:
            print("Exception occurred-", ex)
        finally:
            if Test.file is not None:
                Test.file.close()
                print("\n*****File Closed******")
Test.main()

Output-
	****Read the content at an instance****
	Hi Welcome
	Bye
	****Read the content char by char****
	Hi Welcome
	Bye
	*****File Closed******

Open Function Is Having 3 Modes-

1) “R” –

  • 1) Open the file in read mode.
  • 2) If file is present – It will open the file and will return the pointer.
  • 3) If file is not present – It will raise the exception.

2) “W” –

  • 1) Open the file into the write mode.
  • 2) If file is present – It open the file and remove all the existing content.
  • 3) If file is not present – It will create a new file.

3) “A” –

  • 1) Open the file into the append mode.
  • 2) If file is present – It open the file and place the cursor at the end of the file to add new content.
  • 3) If file is not present – It will create the new file.

Ex-

class Test:
    src = None
    dest = None

    def main():
        try:
            Test.src = open("./test1.txt", "r")
            Test.dest = open("./test1.py", "w")

            for ch in Test.src:
                Test.dest.write(ch)
            print("Data Copied")
        finally:
            if Test.src is not None:
                Test.src.close()
            if Test.dest != None:
                Test.dest.close()

Test.main()

Output-
	Data Copied

    • Qsn-

      How to read the content of CSV(comma separated values) file?

Ans-

import csv #predefined module
file = open("./Test.csv", "r")
print("CSV File Opened")

table = csv.reader(file)
for record in table:
    print(record)
file.close()
print("File Closed")

    • Qsn-

      How to read the content of XLS file?

Ans-

import xlrd
wb = xlrd.open_workbook("Demo1.xlsx")
sheet = wb.sheet_by_index(1)
for i in range(sheet.nrows): #sheet.nrows - Total no of rows
    for j in range(sheet.ncols) :#sheet.ncols - Total no of colomns
        print(sheet.cell_value(i,j), end=' ')
    print()

Output-
	Name Age 
	A2 171.0 
	B2 898.0 
	C2 787.0
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