Constructors

Constructor

In class based object oriented programming constructor is a special member function (or an subroutine) that is called to create object of a particular class. It prepares the object for use.

Properties

> A constructor will have same name as the class (exceptions: python, php, ruby ...)

> It does not have any explicit return type at all not even void. (as they always return the object of the existing class.).

> The constructor is called each time the object declaration is encountered.
> Like other functions constructor also have parameter list, and a (possibly empty) body.
> A class can have multiple constructor.
>Unlike other member function constructor must not declare as const.

Constructor Types

Default Constructor

Default constructor (or synthesized default constructor) is a constructor generated automatically by the C++ compiler in the absence of any programmers defined constructor. A use defined no argument constructor is also called default. A parametrized constructor with all its arguments as default arguments is also called a default constructor.

Programming Problem Two

Problem Statement:   Shashank likes strings in which consecutive characters are different. For example, he likes ABABA, while he dosen't like ABAA. Given a string congaing characters A and B only, he wants to change it to a string he likes. To do so he is allowed to delete the characters in the string. The problem is to fin d the minimum number of deletion required.

For example:

ABBAB -> ABAB (Requires 1 deletion)
AAAAAA -> NULL (Requires 6 deletion)
ABABA -> ABABA (Requires 0 deletion)

C++ Code:

1. #include <iostream>
2. #include <string>
3. #include <cstring>
4. using namespace std;
5. 
   
6. int delRequired(string testString)
7. {
8. size_t size = testString.length();
9. char arr[size+1];
10. strcpy(arr,testString.c_str());
11. int i, noOfDel = 0;
12. for(i = 0; i < size; ++i) {
13. if(arr[i] == arr[i+1]) {
14. noOfDel += 1;
15. }
16. }
17. return noOfDel;
18. }
19. 
    
20. int main()
21. {
22. int testCase, i = 0;
23. cin >> testCase;
24. int delArr[testCase];
25.  
26. while(testCase--) {
27. string testString;
28. cin >> testString;
29. delArr[i++] = delRequired(testString);
30. }
31. delArr[i] = -1;
32. i = 0;
33. while(delArr[i] != -1) {
34. cout << delArr[i] << endl;
35. i += 1;
36. }
37. return 0;
38. }

Programming Problem One

Problem Statement:   Given two numbers (int) L (low) and H (high) , The problem is to find the maximum value of A xor B such that  L ≤ A ≤ B ≤ U.

C++ Code:

1. #include <iostream>
2. using namespace std;
3. 
   
4. int maxXor(int l, int r) 
5. {
6. int max = 0;
7. for (int i = l; i <= r; ++i) {
8. for (int j = l; j <= r; ++j) {
9. if((i ^ j) >= max) {
10. max = i ^ j;
11. }
12. }
13. }
14. return max;
15. }
16.  
17. int main() 
18. {
19. int res, l, r;
20.  
21. cin >> l;
22. cin >> r;
23.  
24. res = maxXor(l, r);
25. cout << res;
26.   return 0;
27. }