Quiz 2 - Part 1

Given (using C++)

int&a = 10;

what is the value of a++

• cannot do address arithmetic on references

• addr(a) + 4

• 11

• a constant cannot be assigned to a reference

In Python, if

a = [10,12,15,16],

what is the value of a after

for (i in len(a)):

a[i]=a[i]+1

• the stmt is meaningless and should be changed to "for (i in range(len(a))):"

• [11,13,16,17]

• the stmt is meaningless and should be changed to "for (i in a):"

• a is immutable and hence illegal

(Python) if a is [1,1,1,1], what is the value of a after

for i in a:

a[i] = a[i]+1

• not a meaningful stmt syntactically

• [1,3,3,1]

• [2,2,2,2]

• index out of range error

Let (C++)

int a = 5; int&i = a;

what is the value of a after

i++; a += 24

• 29

• 30

• aliasing makes the value of a indeterminate

• cannot assign a to i

Stmts like a = a++ are best avoided in C++ because

• cannot have a as lvalue and rvalue in the same stmt

• it can get confused as (a=a)++

• it has unsequenced updates

• it is meaningless as a cannot be equal to its incremented value

int vect[] = {10, 20, 30, 40};

for (int& x: vect) x = x + 5;

What is the value of vect?

• cannot be computed as x does not have an initialization

• as vect is not updated, value remains same as before

• {15,25,35,45}

• vect[] is not a correct decl & hence will not compile

if int a[i] is 10 and a[i] = a[i]+1;

lvalue in the assg is (in C or C++)

• 10

• 11

• addr(a)

• addr(a)+4*i

enum stu_t {BTech, MS, PhD};

enum stu;

int stu = 5;

for the above decls, we get (in C)

• a runtime error

• type mismatch syntax error due to enum and int

• namespace error

• no error

Consider the above prog in Qn. 8 (only 3 stmts),

• it does not compile as there is no main

• it compiles but syntactically wrong

• it compiles but there is a linker error as main is missing

• it executes but there is no output as there is no printf stmt

C does not allow variable number of arguments because:

• if number of arguments is variable, stack mgmt becomes difficult

• it cannot do type checking

• the stmt made is actually false

• it is not part of language but possible as an addon library