Top Python Interview Questions

The objects of string class are immutable. That is, once the strings are created (or initialized), they cannot be modified. No character in the string can be
edited/deleted/added. Instead, one can create a new string using an existing string by imposing any modification required.
Try to attempt following assignment –
>>> st= “Hello World”
>>> st[3]='t'
TypeError: 'str' object does not support item assignment
Here, we are trying to change the 4th character (index 3 means, 4th character as the first index is 0) to t. The error message clearly states that an assignment of new item (a string) is not possible on string object. So, to achieve our requirement, we can create a new string using slices of existing string as below –
>>> st= “Hello World”
>>> st1= st[:3]+ 't' + st[4:]
>>> print(st1)
Helto World #l is replaced by t in new string st1

A function is a block of code which is executed only when it is called. To define a Python function, the def keyword is used.

Example:
def func():
print("Hi, Welcome to ROOTWORKZ")
func(); #calling the function

import re
fname=input("Enter file name:")
try:
fhand=open(fname)
except:
print("File cannot be opened")
exit(0)
for line in fhand:
line=line.rstrip()

if re.search('^([^0-9]*)$',line):
print(line)

fname=input(‘Enter a file name:’)
word=input(‘Enter a word to be searched:’)
fhand=open(fname)
for line in fhand:
if line.startswith(word):
print(line)
fhand.close()