Please help with this review
Please answer the following True or False questions: Chose the best answer
1 String variable X holds ‘Thank’ and variable Y holds ‘You’, then X + Y gives us ‘ThankYou’
2 In python programming, If variable X = ‘2’ and variable Y = ‘3’, then X + Y gives 5
3 A variable is a name for a place in the computer’s memory where you store some data
4 Before reading or writing to a file, a file object must be created via an open method
5 Python is a general-purpose interpreted, interactive, object-oriented, and high-level programming language
6 Python = ‘Hello World!’, python[0] will produce
7 Pseudo-random generators generate true random numbers
8 In python lists are mutable and they have dynamic nature
9 The principles of OOP include polymorphism, encapsulation, inheritance and abstractions
10 Assume the following python code, list = [ ‘abcd’, 786 , 2.23, ‘john’, 70.2 ], list[-1] and list[5] gives us the same output
11 ** operator performs exponential (power) calculation. a**b = 10 to the power 20 if a = 10 and b = 20
12 Break statement terminates the loop statement and transfers execution to the statement immediately following the loop
13 In Python the capitalize() funciton − Converts all lowercase letters in string to uppercase
14 The output of len([1, 2, 3]) is 2
15 list.reverse () sorts objects in a list
Expert Answer
(1)
Both X and Y holds two strings. Both strings can be concatenated in to a single string using + operator.
Hence X + Y gives ‘ThankYou’
Hence given statement is TRUE
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(2)
Both X and Y holds two strings. Operator + concatenates both the strings.
Hence X + Y returns ’23’ but not 5.
Hence given statement is FALSE
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(3)
Variable name is the one used to reference the value stored in memory.
Hence given statement is TRUE
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(4)
Before reading / writing to a file, a file object needs to be created using open method and need to specify the mode of reading(read or write).
For eg:
For Reading: fReader = open(“fileName”, “r”);
For Writing: fWriter = open(“fileName”, “w”);
Hence given statement is TRUE
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(5)
Python language was created by Guido van Rossum during 1985- 1990.
It has following features:
(a) Interpreted – Translates each line of code individually
(b) Interactive – Python comes up with excellent IDE that gives user friendly interactive environment
(c) Object-Oriented – Python offers excellent OOPS features where in reduces complexity and increases usability.
(d) High Level Programming Language – Commands are mostly direct commands specified in high level language.
Hence given statement is TRUE
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(6)
Statement python = ‘Hello World!’; stores the string ‘Hello World!’ in to variable python.
python[0] refers to character ‘H’ present at index 0 of string ‘Hello World!’ pointed by variable python.
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(7)
Pseudo-random number generator (PRNG) are used for generating sequence of numbers that are close to truly random that are generated using hardware random number generators.
Hence given statement is TRUE
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(8)
Python objects (lists, dictionaries) are mutable in nature i.e., With out losing their identity, values can be changed. Hence Lists are considered to mutable in nature.
For eg: myList = [10, 20, 30]
myList[1] = 50; changes the list to myList = [10, 50, 30]
Hence given statement is TRUE
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(9)
OOP Principles:
(a) Polymorphism – Refers to Single name many forms. A function can be defined with same name but tends to exhibit different feature based on Change in Parameters.
(b) Encapsulation – Hides the data and implementation details from outside world.
(c) Inheritance – Refers to object re-usability. Parent class features can be used by child class rather than implementing once again.
(d) Abstraction – It hides all the unwanted data and focuses mostly on its usability rather than on its implementation.
Hence given statement is TRUE
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(10)
Give list declaration, list = [ ‘abcd’, 786 , 2.23, ‘john’, 70.2 ]
List indexing starts from 0 to 4 (both including).
list[-1] refers to last element in the list.
list[5] generates an error as it exceeds the indexing value.
Hence given statement is FALSE
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(11)
Operator ** calculates exponential (power).
For eg: 2**4 returns value 16
Hence given statement is TRUE
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(12)
Break statement terminates the loop statement and transfers execution to the statement immediately following the loop.
For eg:
for ch in ‘Hello World!’:
if letter == ‘r’:
break
print(ch, end=””)
Generates following output:
Hello Wo
(Whenever character r encounters loop gets terminated using break statement and hence output contains Hello Wo)
Hence given statement is TRUE
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(13
Function capitalize() in python turns Starting character of string to upper case and remaining all characters to lower case.
Hence given statement is FALSE
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(14)
Statement len([1, 2, 3]) returns value 3.
[1, 2, 3] is a list. Function len() will return length of the string. As there are three elements in the list. Statement len([1, 2, 3]) returns value 3 but not 2.
Hence given statement is FALSE
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(15)
list.reverse () doesn’t sorts objects in a list. It just reverses the elements of the list.
For eg:
a = [1, 4, 2, 9]
a.reverse() turns a into [9, 2, 4, 1]
Hence given statement is FALSE
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