Day3: Required interview questions

Topic 1

There is a structure like this:

struct A{

long a1;

short a2;

int a3;

int a4;

};

What is the size calculated by sizeof(struct A) under a 64-bit compiler?( ) A

A.24

B.28

C.16

D.18

Analysis:

A. First of all, it is clear that the size of the pointer under 64-bit is 8 bytes, which is the key, a1 occupies 4 bytes, a2 two bytes, since a3 occupies 4 bytes, a2 needs to be filled with 2Byte, for a1, a2, a3, a total of 12 bytes are opened. Since a4 occupies 8 bytes, 4 bytes must be filled after a4 to be an integer multiple of 8, and the final sum is 24 bytes, just rightAlso a multiple of 8, so the final structure size is 24 bytes, answer A

B.Error

C. If the system is 32-bit, the structure size is 16

D. Error

Topic 2

Can a struct in C++ have member functions?( ) B

A. No, struct types do not support member functions

B. May have

C. No, only classes are allowed to have member functions

Analysis:

A.C language structure does not support member functions, but C++ structure supports it. There is no difference between class and struct. The only difference is that by default, the access attribute of class is private and struct is publicp>

B. Correct

C.C++ structs also support member functions

Topic 3

The following statement about the usage of this pointer is correct( )D

A. Ensure that protected members of the base class are accessible in subclasses

B. Ensure that private members of the base class can be accessed in subclasses

C. Ensure that the public members of the base class can be accessed in the subclass

D. Guarantees that each object has its own data members, but shares the code that handles that data

Analysis:

A. The protected members of the base class can be accessed directly in the subclass, regardless of this

B. The private members of the base class cannot be accessed in the subclass, regardless of this

C. The common members of the base class can be accessed directly outside the subclass and the object, regardless of this

D.this pointer represents the current object and can distinguish the own data of each object, so it is correct

Question 4

The error described below is ( ) C

A.this pointer is an implicit parameter of a non-static member function.

B. Every non-static member function has a this pointer.

C.this pointer is stored in the object.

D.this pointer can be null

Analysis:

A. Static member functions do not have this pointer, only non-static member functions have it, and it is a hidden pointer

B. The first parameter of a non-static member function is the hidden this pointer

C.This pointer is in a non-static member function, and the object does not exist, so it is wrong
D. It is not possible to simply assign null to this, but it can be forcedTurn directly to empty, but generally do not do such an operation