C++ :: Discrepancy Between Constructor Output And Following Print Call To Object?
Jul 5, 2013
I am creating a Matrix class, and one of the constructors parses a string into a matrix. However, printing the result of the constructor (this->Print()) prints what I expect, and an <object_just_created>.Print() call returns bogus data. How is this even possible?
Snippets below:
Matrix::Matrix(const string &str) {
// Parse a new matrix from the given string
Matrix r = Matrix::Parse(str);
nRows= r.nRows;
nCols= r.nCols;
[Code] ....
in the driver program, here are the two successive calls
Matrix mm6("[1 2 3.8 4 5; 6 7 8 9 10; 20.4 68.2 1341.2 -15135 -80.9999]");
mm6.Print();
// mm6.Print() calls bogus data, -2.65698e+303 at each location. The matrix's
// underlying array is valid, because printing the addresses yields a block
// of memory 8 bits apart for each location
will copy constructor does object initialization using another already created object? I understand that it can be applied for object initialization and not for assignment.Is it correct?
I get the error at the line "ptr1 = new node;" I tried putting a default constructor for my node struct and that fixed the problem but a new problem arises. It states that i have a linker error after i compile it with a default constructor.
I am confused for first call to push_back copy constructor is called for second call I am expecting it to move class instance to new memory location there by trigering move and then inserting second class instance expected call:
Copy constructor Move constructor Copy constructor but its calling Copy constructor Copy constructor Move constructor
is it possible to get object name in the constructor? I would like to initialize an object of circle class without any arguments and put some pretty lines in constructor to get and save as table of chars the name of creating object. Is it possible? I work with MSVS2012.
To my best understanding, the compiler will provide me with a deafult constructor only if there are no any user defined constructors, at all. Now consider the following code:
Code: class MyClass { private: int m_data; public: MyClass(int init):m_data(init){cout<<"Ctr called"<<endl;}
[Code] ....
How is it that suddenly, there is a default constructor?
I have a program that has a base class 'control' and there are 2 dervied classes 'button' and 'textbox'. How do i make a constructor in the 'button' or 'textbox' that initializes a pointer of the data type 'control' to point to the object that invokes the constructor. the code should look like this
class control { //data } class button:public control { buton() { //code for the constructor } }
actually i have an array of pointers of the type 'control' and as soon as any instance of a control like button or textbox is created the constructor should make an element of the array to point to the instance
Write a constructor that initializes a new inventory object with the values passed as arguments, but which also includes a reasonable default value for each parameter.
C programming, make it use a function call to print the smallest number? this is a program which prints out the smallest of three numbers within the main function that I was asked to write.Now the other question i am asked,5. Re-write the program, uses a function call to print the smallest number?
Code:
# include <stdio.h>
main() { int a,b,c; int temp, min; a = 100; b = 23; c = 5; }
class Base { char * ptr; public: Base(){} Base(char * str)
[code].....
Obj1 is a derived class object where base class char pointer is initialized with "singh" and derived class char pointer is initilized with "sunil". I want to create Obj2 out of Obj1. Separate memory should be created for Obj2 char pointer (base part and derived part as well) and that should be initialized with the strings contained in Obj1.
Here the problem is: Derived class part can be initialized with copy constructor. How to initialize the base class char poniter of Obj2 with the base class part of Obj1. char pointers in both the classes are private.
I tried using initializer list but could not succeed.
At the bottom I have a loop that cout FI,XC,XL,I while going through the loop but when it prints its uneven and setw cant fix it. How do I print values of FI,XC,XL & I to an array so they are aligned.
Finally got to functions. Made a simple one that adds two numbers:
Code: int add(int a, int b){ cout<<"a+b="; return a+b; }
It refuses to give an output unless I use cout.
If I just call the function like so: "add(12, 24);", shouldn't it print out a+b=36? It only prints out "a+b=", unless I use "cout<<" ahead of the call.
My simple question is why does it need cout ahead of the call? Shouldn't "return" do its job and print out the number?
