Data control language: A Data Control Language (DCL) is a programming language used to control the access of data stored in a database. It is used for controlling privileges in the database (Authorization). The privileges are required for performing all the database operations such as creating sequences, views of tables etc.
SQL commands which come under Data Control Language are:

(i) character
(ii) Signed decimal integer
(iii) String

str1 = input ("Enter a string:")
Index=-1
while index >= -(lentstrl1)):
print ("Subscript[",index,"] :" + str1 [index])
index +=-1
Output:
Enter a string: welcome
Subscript [ -1 ] : e
Subscript [ -2 ] : m
Subscript [ -3 ] : 0
Subscript [ -4 ] : c
Subscript [ -5 ] : I
Subscript [ -6 ] : e
Subscript [ -7 ] : w

In line No.8, del F.display will not come.

Variables defined inside a class are called as "Class Variable" and functions are called as "Methods. Class variable and methods are together known as members of the class. The class members should be accessed through objects or instance of class. A class can be defined anywhere in a Python program.
Defining classes: In Python, a class is defined by using the keyword class. Every class has a unique name followed by a colon (:).
Syntax for Defining a Class:
class class_name:
statement_1
statement_2
....................
....................
statement_n

(i) In Python, a string literal is a sequence 0 characters surrounded by quotes. Python supports Single, double and triple quotes for a string.
(ii) A character literal is a single character surrounded by single or double quotes. The value with triple-quote u ''' ''' is used to give multi-line string literal.
Program:
To test String Literals:
# Demo Program to test String Literals
strings = "This is Python"
char = "C"
multiline_str = ''''This is a multiline string with more than one line code.'''
print (strings)
print (char)
print (multiline_str)
# End of the Program
Output:
This is Python
C
This is a multiline string with more than one line code.

(i) Access control is a security technique that regulates who or what can view or use resources in a computing environment.
(ii) It is a fundamental concept in security that minimizes risk to the object.
(iii) In other words access control is a selective restriction of access to data.
(iv) In object oriented programming languages is implemented through access modifiers.

Strings in python are immutable. That means, once you define a string modifications or deletion is not allowed.

(i) Once you define a string, python allocate an index value for its each character.
(ii) These index values are otherwise called as subscript which are used to access and manipulate the strings. The subscript can be positive or negative integer numbers.

The DISTINCT clause is helpful when there is need of avoiding the duplicate values present in any specific columns/table. When we use distinct keyword only the unique values are fetched.

(i) The variables which are defined inside the class is public by default. These variables can be accessed anywhere in the program using dot operator.
(ii) A variable prefixed with double underscore becomes private in nature. These variables can be accessed only within the class

(i) Object - name = class_name ()
(ll) Object - name = class_member

Strings in python are immutable. That means, once you define a string moditications or deletion is not allowed. However, we can replace the existing string entirely with the new string.

//Now select File ➝ New in Notepad and type the Python program
# Save the File as classpy.py
# Python classpy.py -i inheri_cpp command to execute c++ program
Python Program:
import sys, os, getopt
def main (argv):
cpp_file ="
exe_file ="
opts.args= getopt.getopt (argv, "i:",['ifile='])
for o, a in opts:
1ifile. ("'-"1", --ifile"):
cpp_file = a + '.cpp'
exe_file = a + '.exe'
run (cppfile, exe_file)
def run(cpp_file, exe_file):
print ("Compiling" + cpp_file)
os.system ('g++ ' + cpp_file + '-o' + exe_file)
print ("Running" + exe_file)
print ("------------------- ")
print
os.system (exe_file)
print
if __name__ =='__main__"
main (sys.argv[1:])

class test;
def check (self, num)
if num> 0:
print (num, "is positive number")
else:
print (num, "is negative number")
n = test ()
x = int (input("Enter the number"))
n. check (x)

(i) Access control is a security technique that regulates who or what can view or use resources in a computing environment.
(ii) It is a fundamental concept in security that minimizes risk to the object.
(iii) In other words access control is a selective restriction of access to data. IN Object oriented programming languages it is implemented through access modifiers.
(iv) Classical object-oriented languages, such as C++ and Java. control the access to class members by public, private and protected keywords.
(v) Private members of a class are denied access from the outside the class. They can be handled only from within the class.
(vi) Public members (generally methods declared in a class) are accessible from outside the class. The object of the same class is required to invoke a public method. This arrangement of private instance variables and public methods ensures the principle of data encapsulation.
(vii) Protected members of a class are accessible from within the class and are also available to its sub-classes. No other process is permitted access to it. This enables specific resources of the parent class to be inherited by the child class.
(viii) Python doesn't have any mechanism that effectively restricts access to any instance variable or method. Python prescribes a convention of prefixing the name of the variable or method with single or double underscore to emulate the behaviour of protected and private access specifiers.
(ix) All members in a Python class are public by default. whereas by default in C++ and java they are private. Any member can be accessed from outside the class environment in Python which is not possible in C++ and java.

String Operators:
Python provides the following operators for string operations. These operators are useful to manipulate string.
(i) Concatenation (+):
Joining of two or more strings is called as Concatenation. The plus (+) operator is used to concatenate strings in python.
Example:
>>> "welcome" + "Python"
'welcome python'
(ii) Append (+ =):
Adding more strings at the end of an existing string is known as append. The operator += is used to append a new string with an existing string.
Example:
>>> str1 = "welcome to"
>>> str1 + = "Learn Python"
>>> print (str1)
Welcome to Learn Python
(iii) Repeating (*):
The multiplication operator (*) is used to display a string in multiple number of times.
Example:
>>> str1= "welcome "
>>> print (str1 *4)
Welcome Welcome Welcome Welcome
(iv) String slicing:
Slice is a substring of a main string.
A substring can be taken from the original string by using [ ] operator and index or subscript values. Thus [ ] is also known as slicing operator. Using slice operator, we have to slice one or more substrings from a main string.
General format of slice operation:
str[start:end]
Where start is the beginning index and end is the last index value of a character in the string. Python takes the end value less than one from the actual index specified.
Example: I
Slice a single character from a string
>>>str 1 = "THIRUKKURAL"
>>>print (str 1 [0])
       T
(v) Stride when slicing string:

• When the slicing operator, we can specify a third argument as the stride, which refers to the number of characters to move forward after the first character is retrieved from the string.
• The default  value of stride is 1
• Python takes the last value as n-1
• We can also use negative value stride, to print data in reverse order.

Example :
>>>str1 = "Welcome to learn python"
>>>print(str1[::-2])
Output :
nhy re teolW