E1 · Milestone Exam I — The Latency Lab

Milestone Exam I

12 questions · pass at 75%

Q01

The linker reports "undefined reference to foo()". Most likely cause?

Afoo has a syntax errorBfoo is declared but its definition was never compiled/linked inCfoo is called before it is declaredDfoo returns the wrong type

WhyUndefined reference is a link-time error: the declaration exists but no definition was found to link against.

Q02

Signed integer overflow in C++ is:

ADefined wraparoundBUndefined behaviorCA compile errorDAutomatically promoted to long

WhySigned overflow is UB. Unsigned overflow is defined wraparound.

Q03

Why represent a price of $150.25 as the integer 15025?

AIntegers print fasterBTo avoid floating-point rounding and comparison errorsCdouble cannot hold 150.25DIt uses less memory

WhyDoubles cannot exactly represent most decimals, breaking equality and accumulating error. Integer ticks are exact.

Q04

A local variable inside a function lives on the ___ and is destroyed when ___.

Aheap; the program endsBstack; the function returnsCheap; you call deleteDstack; you call delete

WhyAutomatic storage: stack, destroyed at scope exit.

Q05

Which is a use-after-free bug?

AAllocating with new and never deletingBDeleting a pointer then dereferencing itCDeleting the same pointer twiceDTaking the address of a local

WhyUse-after-free = accessing memory after it was freed. (A) is a leak, (C) is double-free.

Q06

const int* p means:

Aconst pointer, mutable dataBmutable pointer, const dataCboth constDboth mutable

Whyconst left of * binds the data: the pointee is read-only, the pointer can be reseated.

Q07

int* const p means:

Aconst pointer, mutable dataBmutable pointer, const dataCboth constDboth mutable

Whyconst right of * binds the pointer: fixed address, but the pointed-to int can change.

Q08

p[3] for a pointer p is equivalent to:

A*(p + 3 bytes)B*(p + 3) advanced by 3 elementsCthe 3rd byte of pDp + 3

Whyp[i] == *(p + i); pointer arithmetic scales by element size.

Q09

A function returns &local. The caller then dereferences it. This is:

AFineBA memory leakCA dangling pointer / undefined behaviorDA double free

WhyThe local dies at return; its address is dangling. Using it is UB.

Q10

The single default difference between struct and class is:

Astruct cannot have methodsBdefault access: struct public, class privateCclass cannot be on the stackDstruct cannot have a destructor

WhyOnly the default member access differs.

Q11

Members of a class are initialized in:

Ainitializer-list orderBdeclaration orderCalphabetical orderDconstructor-call order

WhyAlways declaration order, regardless of how you write the initializer list.

Q12

RAII means:

Amanual cleanup at each call siteBacquire a resource in the constructor, release it in the destructorCgarbage collection for C++Dallocating everything on the heap

WhyRAII binds resource lifetime to object lifetime; the destructor releases on every exit path.

Fundamentals → RAII

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Milestone Exam I