module 1

Question 1

Write an example of an int named n that assigned the value 2 using the Uniform Initialization Syntax.

Answer 1

int n{2};

Question 2

Rewrite this array initialization using the Uniform Initialization Syntax

int a[] = {1, 2, 3};

Answer 2

int a[]{1, 2, 3};

Question 3

Is the following a declaration, a definition, or both?

int x;

Answer 3

both

Question 4

Is the following a declaration, a definition, or both?

void f(int);

Answer 4

Declaration

Question 5

What type does the .size() method return?

Answer 5

size_t

Question 6

What standard library must be included in order to use the type size_t?

Answer 6

#include <cstddef>

Question 7

Which of the following is the best practice way to change the type of x to an int and store it in n?

// a)
int n = static_cast<int>(x);
// b)
int n = int(x);
// c)
int n = (int)x;

Answer 7

option b; function-style “casts”

Question 8

Which of the following is the worst practice way to change the type of x to an int and store it in n?

// a)
int n = static_cast<int>(x);
// b)
int n = int(x);
// c)
int n = (int)x;

Answer 8

option c; never use C/Java?C# style casts

Question 9

Declare a variable called p that is a pointer to an int.

Answer 9

int* p;

Question 10

What pointer type can only hold an address, and cannot be dereferenced?

Answer 10

void*

Question 11

Given the following code:

#include <iostream>
using namespace std;

int main()
{
    int   i = 7;
    int*  ip = &i;
    int** ipp = &ip;
}

What is **ipp?

Answer 11

7; the rvalue of i

Question 12

Given the following code:

#include <iostream>
using namespace std;

int main()
{
    int   i = 7;
    int*  ip = &i;
    int** ipp = &ip;
}

What is *ipp?

Answer 12

a pointer to an int; the lvalue of ip

Question 13

Given the following code:

#include <iostream>
using namespace std;

int main()
{
    int   i = 7;
    int*  ip = &i;
    int** ipp = &ip;
}

What is ipp?

Answer 13

a pointer to a pointer to an int; the lvalue of ipp

Question 14

Given the following code, which line will throw an error?
~~~
\ given:
const char * p1;
\ a)
*p1 = ‘c’;
\ b)
++p1;
~~~

Answer 14

Line a throws an error

const before the asterisk will const the contents

Question 15

Given the following code, which line will throw an error?
~~~
\ given:
char const * p1;
\ a)
*p1 = ‘c’;
\ b)
++p1;
~~~

Answer 15

Line a throws an error

const before the asterisk will const the contents

Question 16

Given the following code, which line will throw an error?
~~~
\ given:
char * const p1;
\ a)
*p1 = ‘c’;
\ b)
++p1;
~~~

Answer 16

line b will throw an error

const after the asterisk will const the pointer

Question 17

Given the following code, which line will throw an error?
~~~
\ given:
const char * const p1;
\ a)
*p1 = ‘c’;
\ b)
++p1;
~~~

Answer 17

Trick question, they will both throw an error

Question 18

Write a void function called inspect() that will take a const void* and the number of bytes as parameters and prints the bytes of the object.

print in hex, with each byte separated by a space

Answer 18

#include <iostream>
#include <cstddef>
#include <iomanip>

using namespace std;

void inspect(const void* ptr, size_t num_bytes) {
    const unsigned char* char_ptr = static_cast<const unsigned char*>(ptr);
    cout.setf(ios::hex, ios::basefield);
    for (size_t i = 0; i < num_bytes; ++i) {
        cout << setw(2) << setfill('0') << int(char_ptr[i]) << " ";
    }
}

Question 19

What does the following line do?
cout.setf(ios::hex, ios::basefield);

Answer 19

it alters how an int will be output; ios::basefield acts as a mask to clear any previously set base format, and ios::hex will then set the current bitmask to hex so all subsequent int objects will be output with a hexadecimal base

Question 20

What will the following code output?

#include <iostream>

int main()
{
    using namespace std;
    int i = 7;
    int& r = i;
    
    \++r;
    cout << i << endl;
}

Answer 20

8

r is another name for the existing local variable i

Question 21

Write a function called swap() that will take two int objects and swap their rvalues.

Answer 21

void swap(int& a, int& b) {
    int temp = a;
    a = b;
    b = temp;
}

Question 22

Write the function called current() that will operate according to the following code:
~~~
#include <iostream></iostream>

int a[4] = {0,1,2,3};
int index = 0;
int main()
{
using namespace std;
current() = 10; // replace a[0]
index = 3;
current() = 20; // replace a[3]
for (int i = 0; i < 4; ++i)
cout &laquo_space;a[i] &laquo_space;‘ ‘;
cout &laquo_space;endl;
}
// Output -> 10 1 2 20
~~~

Answer 22

int& current()		// Returns a reference
{
    return a[index];
}

Question 23

Given the following code, what will i be?

int i = 42;
int &r1 = i;
const int &r2 = i;
r1 = 0;

Answer 23

i will be 0

Question 24

Given the following code, what will r1 be?

int i = 42;
int &r1 = i;
const int &r2 = i;
r1 = 0;

Answer 24

r1 will be 0

Question 25

Given the following code, what will `r2` be? ``` int i = 42; int &r1 = i; const int &r2 = i; r1 = 0; ```

Answer 25

`r2` will be `0` | `r2` cannot directly be changed (`r2 = 5`), but changes with `i` or `r1`

Question 26

Write a for loop that will convert each char in the following string, `s`, to uppercase: ``` string s{"Hello World!!!"}; // for loop here cout << s << endl; // output -> HELLO WORLD!!! ```

Answer 26

``` for (auto &c : s) { c = toupper(c); } ```

Question 27

What is the output of the following code? ``` int a[5]{1, 2, 3, 4, 5}; cout << *a << endl; ```

Answer 27

1 (`*a == a[0]`) | array name in expression == pointer to the first element

Question 28

What is the output of the following code? ``` int a[5]{1, 2, 3, 4, 5}; int i = 3; cout << *(a + i) << endl; ```

Answer 28

4 | `*(a + i) == a[i]`

Question 29

Write an example of the `strcpy()` function defined in the `` library.

Answer 29

``` char a[] = "Hello"; char b[10]; strcpy(b, a); ``` | `strcpy()` is unsafe

Question 30

What happens if the destination in `strcpy()` does not have enough room reserved?

Answer 30

It keeps going and overwrites other variables; this is a common security vulnerablility called "buffer overrun" | this is why it is unsafe to use `strcpy()`

Question 31

Given `int a[n];` where `n` is a `const`, what is an idiom find `n`?

Answer 31

``` n == sizeof(a) / sizeof(a[0]); ```

Question 32

What will the following code output? ``` int a[] {1, 2, 3, 4, 5}; int* p = a + 1; cout << p - a << endl; ```

Answer 32

1

Question 33

What will the following code output? ``` int a[] {1, 2, 3, 4, 5}; int* p = a + 1; int* q = a + 4; cout << q - p << endl; ```

Answer 33

3

Question 34

What will the following code output? ``` int a[2][3]; cout << sizeof(a) << endl; ```

Answer 34

24