OAU CSC 201 Practice Quiz

Explanation: { } creates a dictionary not a set. Only set() creates an empty set.

Dictionary stores values in terms of keys and values.

Objects of type set have no attribute values.

Expression 1 is evaluated as: 2**9, which is equal to 512. Expression 2 is evaluated as 8**2, which is equal to 64. The last expression is evaluated as 2**(3**2). This is because the associativity of ** operator is from right to left. Hence the result of the third expression is 512.

Padding is done towards the right-hand-side first when the final string is of even length.

The code shown above displays the string method to round off a given decimal number to two decimal places. Hence the output of the code is: ‘1.23’.

The first letter of the string is converted to uppercase and the others are converted to lowercase.

The output of the expression above will be 22.19. This expression specifies that the total number of digits (including the decimal point) should be 5, rounded off to two decimal places.

The expression not(-6<0 or -6>10) returns the output False.
The expression -6>=0 and -6<=10 returns the output False.
The expression not(-6<10 or -6==10) returns the output False.
The expression not(-6>10 or -6==10) returns the output True.

You can’t perform mathematical operation on string even if the string is in the form: ‘1234…’.

Control exits the loop when i becomes 7.

When the value of x is equal to 8 (1000), then x>>2 (bitwise right shift) yields the value 0010, which is equal to 2. Hence the value of x is 8.

As Python has no concept of private variables, leading underscores are used to indicate variables that must not be accessed from outside the class.

For order of precedence, just remember this PEMDAS (similar to BODMAS).

Explanation: Objects of type int aren’t subscriptable. However, if the statement was x[i], an error would not have been thrown.

The elements of the tuple are accessed by their indices.

All of the above examples show explicit conversion. However the expression int(’10.8’) results in an error.

The code shown above rounds the floating point value to two decimal places. In this code, a variety of addition formatting features such as zero padding, total field width etc. Hence the output of this code is: ‘3.35 | 03.35 | +003.3’.

The result of the expression shown will be 1011. This is because we have not specified the base in this expression. Hence it automatically takes the base as 10.

To write single-line comments in Python use the Hash character (#) at the beginning of the line. It is also called number sign or pound sign. To write multi-line comments, close the text between triple quotes.
Example: “”” comment
text “””

The code shown above prints the values substituted for p and q in the same order. Note that there is no blank space between p and q. Hence the output is: sanfoundry.

The code shown above shows two functions. In both the cases the right operand is returned. This is because each function is evaluated from left to right. Since the left operand is false, it is assumed that the right operand must be true and hence the right operand is returned in each of the above case.

The def keyword is used to create, (or define) a function in python.

The function seed is a function which is present in the random module. The functions sqrt and factorial are a part of the math module. The print function is a built-in function which prints a value directly to the system output.

abcd a a a is the output as x is modified only after ‘abcd’ has been printed once.

The code shown above prints the appropriate option depending on the conditions given. The condition which matches is (9>0), and hence the output is: good.

Lists should be copied by executing [:] operation.

The order of precedence is: %, +.

Hence the expression above, on simplification results in 4 + 3 = 7.

Hence the result is 7.

The code shown above prints the values substituted for a, b, a, in the same order. This operation is performed using the format function. Hence the output of the code is: ‘helloworldhello’.

l (or L) stands for long.

The code shown above uses multiple decorators. The output of this code is:

    *****
    %%%%%
    hello
    %%%%%
    *****

[::-1] reverses the list.

SyntaxError, there shouldn’t be a space between + and = in +=.

Numbers starting with a 0 are octal numbers but 9 isn’t allowed in octal numbers.

The built in function vars() returns a dictionary containing all the variables that exist in the place. Hence the output of the code shown above is: {‘a’ : ‘hello’, ‘q’ : 10, ……..plus built-in names set by Python….}

Variable names can be of any length.

Error, objects of type int aren’t iterable.

All the statements will execute successfully but at the cost of reduced readability.

The line of code shown above can be simplified to state that ‘hello’ should be printed if the argument passed to the Boolean function amounts to zero, else ‘morning’ will be printed.

The string x is being shortened by one character in each iteration.

The value of the expression (2**2)**3 = 4**3 = 64. When the expression 2**2**3 is evaluated in python, we get the result as 256, because this expression is evaluated as 2**(2**3). This is because the associativity of exponentiation operator (**) is from right to left and not from left to right.

~x is equivalent to -(x+1).

Functions are reusable pieces of programs. They allow you to give a name to a block of statements, allowing you to run that block using the specified name anywhere in your program and any number of times.

The code shown above returns the address on the function ordi first, after which the word “Ordinary” is printed. Hence the output of this code is:
Address
Ordinary.

i takes values 0, 1, 2 and 3.

In python, power operator is x**y i.e. 2**3=8.

(element,) is not the same as element. It is a tuple with one item.

String formatting also allows conversion targets on the left to refer to the keys in a dictionary coded on the right and fetch the corresponding values. In the code shown above, (qty) and (food) in the format string on the left refers to keys in the dictionary literal on the right and fetch their assorted values. Hence the output of the code shown above is: 1 more spam.

range(0) is empty