C/C++ Interview Exam (周奕呈)
=================================

1. Where in memory are the variables stored?

* Global variables
* Static variables
* Constant data types
* Local variables (declared and defined in functions)
* Variables declared in *main* function
* Dynamically allocated space

    Please answer here...
    * 
    * 
    * 
    * 
    * 
    * 

2. What are the modifiers "volatile" and "mutable"? When should they be used?

    Please answer here...
    

3. Are the following legal or illegal uses of const pointers? Which lines are illegal ones? What are the benefits of using const?

~~~c
// Question 3
const char *str = "hello";
char c = *str;
str++;
*str = 'a';
str[1] = 'b';
~~~

    str++; is illegal
    Benefits are
    1. 預防數值被更改
    2. 可當作常數使用 例如pi = 3.1415 若設定為const 則variable可視為同等數值
    

4. What is the output of the following program?

~~~c++
// Question 4
#include <iostream>

class A
{
public:
A(int n = 0)
: m_n(n)
{
std::cout << 'd';
}

A(const A& a)
: m_n(a.m_n)
{
std::cout << 'c';
}

private:
int m_n;
};

void f(const A &a1, const A &a2 = A())
{
}

int main()
{
A a(2), b;
const A c(a), &d = c, e = b;
b = d;
A *p = new A(c), *q = &a;
static_cast<void>(q);
delete p;
f(3);
std::cout << std::endl;

return 0;
}
~~~

    Please answer here...
    ddccd
    

5. Please write a function to shuffle a vector of integers.

~~~c++
// Question 5
#include <vector>
#include <stdexcept>
#include <iostream>

class Shuffler
{
public:
static void shuffle(std::vector<int>& sequence)
{
// TODO: Waiting to be implemented
std::vector<int> temp, tempSort;
for (int i = 0; i<6; i++)
{
int timeV = getCurrentTime();
int Value = rand(timeV);
temp.push_back(Value);
tempSort.push_back(Value);
}
tempSort.sort();
for (int i= 0; i<6; i++)
{
for (int j=0; j<6; j++)
{
if (temp[j]==tempSort[i])
sequence[j] = i+1;
}
}

}
};

#ifndef RunTests
int main()
{
std::vector<int> v = { 1, 2, 3, 4, 5, 6 };
Shuffler::shuffle(v);
return 0;
}
#endif
~~~

6. Implement function *countNumbers* that accepts a sorted vector of integers and counts the number of vector elements that are less than the parameter *lessThan*. For example, the following program should return 2 because there are two vector elements less than 4. (Note: the vector size may be extremely large.)

~~~c++
// Question 6
#include <vector>
#include <stdexcept>
#include <iostream>

class SortedSearch
{
public:
static int countNumbers(
const std::vector<int>& sortedVector, int lessThan)
{
// TODO: Waiting to be implemented
if (sortedVector.size()<1)
return 0;
int l = 0, r = sortedVector.size()-1;
int m;
do
{
m = l+(r-l)/2;
if (sortedVector[m]<lessThan)
{
l = m+1;
continue;
}
if (sortedVector[m]>lessThan)
{
r = m-1;
continue;
}
if (sortedVector[m]==lessThan)
return m+1;
}
while (l<r);
return l+1;

}
};

#ifndef RunTests
int main()
{
std::vector<int> v = { 1, 3, 5, 7 };
std::cout << SortedSearch::countNumbers(v, 4);
return 0;
}
#endif
~~~

7. The following code is for inserting an element at the front of a list. Please correct it if you find anything inappropriate, and describe what you find.

~~~c++
struct IntElement
{
int data;
IntElement *next;
};

bool insertInFront (IntElement *head, int data) {
IntElement *newElem = new IntElement;
if (!newElem) return false;

newElem->data;
head = newElem;

return true;
}
~~~

   Please describe what you find here ...
   newElem->data; 沒有給data
   head = newElem; 有給head 但原本的head沒有串上去 就遺失了
   

~~~c++
// Please write the correct code here...
bool insertInFront (IntElement *head, int data) {
IntElement *newElem = new IntElement;
if (!newElem) return false;

newElem->data = data;
newElem->next = head;
head = newElem;

return true;
}

~~~