I have an array of pointers to Mat objects (an OpenCV class used to hold info and data about an image), which I will use to store the images. The function imread reads an image and returns a Mat object loaded with the relevant data about the image.However, this gives me a nice segfault when the assignment takes place. Of course, I can swap it with the following code, but since I'm working with big images (2048x2048 and upwards), it's really inefficient:
for(unsigned int i = 0; i < MAX_IMAGES; i++) {
imageName[11] = 49 + i;
datacube[i] = new Mat(imread(imageName, -1));
}
Is there any way to do this elegantly and without much hassle?Again, excuse my rustiness and anything completely stupid I might have said. It's been a long time since I worked with C++. Managed to circumvent the problem by using a STD vector instead of an array. I'd still like to know the answer to this riddle...
I designed a class template to create unique arrays. I was able to successfully input data to and output data from my array objects, irrespective of the datatype. However, I can't for the life of me fathom why my overloaded assignment operator worked perfectly well only for integer datatype and not for double/string datatypes.
Here is the class definition:
template <class dataType> class myArray { public: void setArrayData();
[code]....
And here is the definition of the overloaded assignment operator:
And here is my main function that tests the operations on objects of the class:
int main(){ //object declarations myArray<double> list(5); //a single-parameter object declaration of class myArray myArray<double> myList(2,13); //a two-parameter object declaration of class myArray
[code]....
The problem I'm having starts from where the assignment operator is being tested: for double and string datatypes, the upper input/output section works fine, but the assignment section freezes the display until the program execution is manually terminated!
I have a data structure defined up here called this:
typedef list <classSpec*> ClassSpecList;
I'm trying to add stuff into the list here based on functions that return certain values of that match the same data type. In one function, I have a list pointer object defined here and I have another statement that calls a function.
Im creating a program for a race. The Race class has a vector of results and each element of that vector is a pointer to a result. The Result class has a Time and a pointer to a Participant. So in each race there are various results and it is a result for each participant.The Time is a class that has hours, minutes and seconds. How can I sort the vector of results from the result of the participant with the fastest time to the result of the participant with the slowest time?My code is like this:
//.h file: class Time { unsigned int hours; unsigned int minutes; unsigned int seconds;
Im creating a program for a race. The Race class has a vector of results and each element of that vector is a pointer to a result. The Result class has a Time and a pointer to a Participant. So in each race there are various results and it is a result for each participant. The Time is a class that has hours, minutes and seconds. How can I sort the vector of results from the result of the participant with the fastest time to the result of the participant with the slowest time?
Im getting some errors in my code. I put the error as comments in the code. Each error is after the line where it occurs. My code is like this:
Using SFML, I had a Board class which held multiple vectors of all of my object types in the game, and then it also held a vector of pointers to the memory addresses of these object instances, like this
class Board{ //... std::vector<AbstractObject*> GetAllLevelObjects(){ return allLevelObjects; } //so these are used to hold my object instances for each level
[Code]....
When looping through this vector and drawing the sprites of the objects, I get the runtime error 0xC0000005: Access violation reading location 0x00277000. I solved this error by storing the vector of pointers in the class that holds my Board instance, but I'm wondering why only this solution worked? Why couldn't I just have my vector of pointers in the same class that the instances of those objects were in?
Code: void Class1::Func(shared_ptr<type1> parameter) { } or void Class1::Func(const shared_ptr<type1>& parameter) { } or Should I ever pass arguments/parameters to other objects using shared_ptr's or raw pointers?
#include <string> #include <vector> using namespace std; class Question { string title; vector<Thing*> posAns; vector<Thing*> negAns;
[Code] ....
error: no instance of overloaded function 'std::vector::push_back()' matches the arguments list argument types are (const Thing *) object type is: std:: vector<Thing *, std::allocator<Thing *>>
So it cannot be constant, what if I just leave it non-constant? Will it be safe?
#include <iostream> using namespace std; class superclass; class subclass1; class subclass2;
[Code] ....
As you can see I want to create a dynamically allocated storage of references to a parent class each of which can then point to a child class, how ever I do not know how to extract the child class out again from that array so i may access its variable b.
This has been bothering me for a while now, and I finally put together an example:
#include <iostream> #include <string> using namespace::std;
[Code]....
In the code above, the two classes hold pointers to each other, and that's fine but it doesn't seem right since C++ prefers to pass by reference. Yes, it can still do that (see testbox and testball) but even that seems odd to me because still you need to use pointer notation for the enclosed object. Am I the only one who feels this way, and should I just get over it? Or am I missing something that would allow an object to hold a reference?
I am a little confused while comparing char pointers to integer pointers. Here is the problem:
Consider the following statement; char *ptr = "Hello"; char cArr[] = "Hello";
When I do cout << ptr; it prints Hello, same is the case with the statement cout << cArr;
As ptr and cArr are pointers, they should print addresses rather than contents, but if I have an interger array i.e. int iArr[] = {1, 2, 3};
If I cout << iArr; it displays the expected result(i.e. prints address) but pointers to character array while outputting doesn't show the address but shows the contents, Why??
I pretty much got the assignment done. All it asked for was that you make a C program that displays which manufacturer owned a disk drive based on the code entered. Pretty simple. Just enter 1, 2, 3, or 4 and get the associated manufacturer. Though I am trying to implement an error messege to it for any interger that isn't 1-4.
Code: #include <stdio.h> int main() {
[Code]...
o errors are given and it works fine as long as you enter 1-4, but when you enter any other didgit it just stops the program without any messeges.
I am working on a double linked list and inside of my function to insert a node, I am getting an error of "Incompatible types in assignment". Here is my function code. Line 55 is where I am receiving the error.
I have code here that uses assignment operators that doesn't return by reference and it still works. So why does my book say you need to return by reference?
Here is a quote from my book:
The return type of operator= is a reference to the invoking object, so as to allow chained assignments a=b=c.
The code below is from my book. I simply removed '&', in the original code that has assignment operators return by reference, from IntCell & operator=. This way the assignment operator no longer returns a reference, and it still works.
#include <iostream> using namespace std; class IntCell { public: explicit IntCell( int initialValue = 0 ) { storedValue = new int{ initialValue }; }
I am wondering why return type for an assignment operator cant be a void or int? Cant I write assignment operator for student class like this as we do nothing with returned value?
Student { char name[20]; int marks; public: student(char*name,int marks)
The task is to use the assignment operator of a class, but change all the data except certain ones. For example, below we are to assign all Person data of 'other' except for 'name' and 'ID':
#include <iostream> #include <string> struct Person { std::string name; int ID, age, height, weight;
[Code] .....
Name = Bob ID = 2047 Age = 38 Height = 183 Weight = 170
Name = Frank ID = 5025 Age = 25 Height = 190 Weight = 205
Bob pretends to be Frank, but keeps his name and ID.
Name = Bob ID = 2047 Age = 25 Height = 190 Weight = 205
But I think the way I did it is pretty lousy (note the wasted steps changing the name and ID only to revert them back? So the ideal solution should require no wasted steps, unlike the method above, and changes to what the exclusions should be should be in only one place (not two like above). Of course, we assume that Person shall have many, many data members (and constantly increasing), so that simply defining Person::operator= (const Person& other) to handle all data except for 'name' and 'ID' is out of the question.
How do i write main test program to test the copy constructor and assignment operator in this program...how do i know if its working as its suppose to?i just want to know about copy and assignment operator..i have figured out the test program for other things..Here my program :
I've been working on some project and I got to wondering when you know you need to use a copy constructor and an assignment operator. Is there a rule of thumb? I know there is the Rule of Three, but is there something that tells you when you need those three?
when i compile the following program i get a compiler warning, but i don't understand why. for me the code seems to be all right and does legitimate this warning. so here is the code
