Assignment 3

Correct answer: B

Explanation: The second statement assigns the value "hello" to x and that overwrites the previous value 10. The type of x afterthe second statement is str

Correct answer: Only B is true

Explanation:

1. A is false because a list is mutable and the value of its elements can be changed.
2. B is true because a list can contain elements of different types and there is no restriction that all elements must be of the same type as in the case of an array
3. C is bfalse because a list can contain other lists
4. D is false as its size is not fixed. It can be increased using append() or insert() methods and decreased using 1pop()orremove()` methods.

Correct answer: B

Explanation: The length of a list returned by the function len() is the number of elements in a list. Elements of a list can be of differetnt types, and a list can contain other lists as its elements. The list after the a.append([4, 5]) is a = [1, 2, 3, [4, 5]]. The last element is a list [4, 5] and is counted as one element not two elements. Therefore the number of elements in a is 4. The length of a[3] is 2.

Correct answer: A

Explanation: The start value is 2, the stop value (the element generated by the range is less than this value) is 10 and step is 3. Thus the sequence is 2, 5, 8, 11, 14,.... Since the stop value is 10, the range consists of only those values less than the stop value. Thus the result is 2, 5, 8. Note: The stop valus itself is not included in the range.

Correct answer: B

Explanation: Here start = 0 since it is not specified (for start to be specified, there must be at least two arguments to range()). stop = 3 (when only one argument is specified) and step = 1 (for step to be specified, there must be three arguments to range()). Thus the series is 0, 1, 2, 3, 4, .... Since the stop = 3, only the values less than 3 are included in the range. Thus the result is 0, 1, 2.

Correct answer: C

Explanation:

1. A is false. Depending on the values of different variables, it is possible that the logical expression at the start of the while loop may evaluate to False, in which case the loop may not be executed even once.
2. B is false. The number of times a while loop executes is determined by the initial values of variables, the logical expression evaluated at the start of the loop and thechanges made to the controlling variables within the loop. This does not guarantee that the loop executes a fixed number of times.
3. C is true. The while loop executes as long as the logical expression at the start of the loop evaluates to True.
4. D is false. There is no restriction on nesting a while loop within an outer while loop.

Correct answer: C

Explanation: On the second iteration of the for loop, x = 0 and 10 / 0 results in ZeroDivisionError exception and the loop is interrupted.

Correct answer: B

Explanation: The continue skips the rest of the statements in the loop only for the current iteration and will continue to the next iteration.

Correct answer: C

Explanation: The number of additional places in a field width of 5 is 5 - len(x) which is 2. Then there is one place on either side of the string x. Since the second argument is -, the places on either side of the string are filled with -, resulting in -abc-.

Correct answer: B

Explanation:

1. A is invalid. The parentheses following the function name func are required, not optional.
2. B is valid.
3. C is invalid. Keyword to start a function definition is def, not function.
4. D is invalid. Name of the function func must be floowed by parentheses, not square brackets.

Correct answer: C

Explanation: When a function requires to return multiple output values, they are bundled together into a single tuple and returned to the parent function. While on the surface it appears that the function is returning multiple items, it is in fact returning a single object with multiple elements contained in it. The result returned is a tuple and not a list because a tuple is immutable, that is, the values returned cannot be changed. They can be copied into other objects in order to change the copies but the original elements returned are immutable.

Correct answer: C

Explanation:

1. A is incorrect. Parameter names need not match argument names although they can if you wish
2. B is incorrect. Type annotations are optional and only indicate intent. The Python interpreter ignores the type annotations. Some code editors use them to prompt programmers to show the intent of the designer of the function.
3. C is correct. Values of the arguements take the place of the parameters for each invocation of the function.
4. D is incorrect. It is permitted to have zero parameters for a function.

Correct answer: B

Explanation: The statement b = a makes b an alias (alternate name) for a. This can be verified by checking that a is b evaluates to True. Thus, any change made to a automatically reflects in b, as it is merely another name by which we refer to a.

Correct answer: C

Explanation: A range is not a collection but what in Python is called a generator. While it generates a sequence of values, it does so one at a time. On the otherhand, a collection such a list, tuple or a set is collection of zero or more elements all stored in memory at the same time, not one at a time. We can create a list, tuple or a set from a range quite easily, using list(range(5)), tuple(range(5)) or set(range(5)).

Correct answer: A

Explanation: This expression is evaluated by generating a (list(range(1, 5))), which is [1, 2, 3, 4] and testing if 3 is in it, which it does. Therefore it returns True.