C++ :: Error With Function With Objects As Parameters
Apr 9, 2013
I am creating code for a group project in my class. All my group members made a header file with an object in it with their functions. One of the functions in my partner's code uses a data member of mine in the function, so she has the function parameter a object of my object. (This isn't the code but for example)
class B {
friend class A;
void displayAthing(A object) {
cout<<object.thing<<endl;
}
I have this when I call the function in the cpp file
int main() {
A object;
B b;
b.displayAthing(object);
return 0;
}
However, when I compile, it gives me an error that the function does not take 1 arguments.
#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?
In my program I created three separate return functions. Each function is labeled:
int boxes(int x, int y); int leftOver(int x, int y); double avgItemsShipped(int x, int y, int z);
Is it bad programming practice to use 'x' and 'y' in all of my functions? Should I use the this keyword inside the function? We use this often in my Java class and I know it exists in C++, but I haven't actually seen it used (or used it myself yet).
So in this function it is already passing the array into the function but the thing is one parameter being passed into the function and if so how do I go about passing 3 arrays as parameters into the function? Also the program only asks for a user entry of hours for three different cars so why would there be a point in making two additional arrays to be passed into the function?
#include <iostream> #include <iomanip> using namespace std; //passing array into function double calculateCharges(double hours[], int HoursArrayLocation);//call function
So I was reading my book and it listed this piece of code. The first piece of code is in the book and the 2nd is just my test on the piece of code. I am curious as to why in the functions parameters there is a reference to aString. I've noticed that removing it has no affect on the outcome of the code.
So I'm writing a data structure from scratch as part of a university assignment in c++, and I have to write an iterator for it. The problem involves comparison between constant iterators and normal iterators, and I'm going about it in this way: I wrote a constructor of normal iterator which takes a const iterator as its only parameter, hoping that the comparison operator between two normal iterators will be enough:
btree<int> bl(5);//the data structure auto iter = bl.begin(); iter != bl.cend(); //trying to compare iterator with const iterator
but apparently this is wrong, since the compiler tells me something along the line of "no function 'operator!=' which takes ......" It seems the constructor is alright, since the following works:
btree<int>::iterator i(bl.cend());
Am I getting something fundamentally wrong about it? How is this functionality actually implemented in C++ library containers like vector?
I noticed that when using variadic functions, if I pass the va_arg() as parameter to a function, the parameters get passed in reverse. Is that expected?
For example, the following code outputs Code: 1 2 2 1
Need setting up counters for this program which should
Given a file of text, assume that a "word" is 1 or more consecutive, non-whitespace characters a "sentence" is a series of words terminated by either a period, exclamation point, or question mark
Design a C++ program (using functions/passing parameters) that will
-interactively prompt for and read the name of an input file -interactively prompt for and read a string to search for -open the input file (using an input filestream variable) and with one pass through the file -count the number of "words" in the file -for each word, make sure all letters, except the first, are lower case - leave the first character unchanged -count the number of "sentences" in the file -count the number of letters in the file (A-Z,a-z) -count the number of consonants in the file (consonants are letters that are not vowels - the vowels are: a, e, i, o, u, A, E, I, O, and U) -count the number of nonwhitespace characters in the file that are NOT letters -count the number of times the search string is found in the file (must be an exact match) - search for matches AFTER upper case letters have been coverted to lower case
test.cpp: In function ‘int main()’: test.cpp:20:30: error: no matching function for call to ‘func1(std::vector<int>&)’ test.cpp:20:30: note: candidate is: test.cpp:8:45: note: template<class T, class U> std::map<T, T> func1(U) test.cpp:8:45: note: template argument deduction/substitution failed: test.cpp:20:30: note: couldn't deduce template parameter ‘T’
I'm using the Visual C++ Express 2008 and i need to pass as parameters to a function characters coded in UTF 8. My environment is Windows 7. The editor of the VC++ write in UTF 8 or UTF 16? If it writes in UTF 16 how can i change it?
I have been experimenting with variadic templates with the aim of caching a call to a class method by storing away the object pointer, method pointer and parameters. I've actually had some reasonable success but have now hit a stumbling block. I now wish to wrap my parameters in a simple template class when I cache them. My success is as follows:
Using variadic template functions to store these pointers and paremeters;
I'm able to pass a method pointer and unwrapped parametersI'm able to pass wrapped parameters on their own.I'm NOT able to pass a method pointer and wrapped parameters I set up a little prototype project to demonstrate the issue and added comments above the function calls to indicate the compilation results. Here is the code:
Code: #include "stdafx.h" ////////////////////////////////////////////////// // Basic class with a simple method ////////////////////////////////////////////////// class MyClass { public: char Method( int i, float f ) { return 'A';
[code]....
But I'm convinced it should take three arguments, the method pointer and two wrapped parameters. Visual studio even suggested it should as shown below:
I'm trying to write a simple Delegate class with a Bind() and Invoke() function. For now it only needs to support a void class function with no parameters. I've searched around and found quite a few exmaples, though, those class are heavily templated and I lose track trying to simplify it.
So far my code is following:
Code: #include <windows.h> class Test { public: void DoSomething() { MessageBox(NULL, L"Test::DoSomething!", NULL, 0);
[Code] ....
The part I am having difficulty with is assigning &Test::DoSomething to the m_Callback variable.
&tObject::DoSomething works, yet _Callback which I pass &Test::DoSomething to does not work.
I am having a problem with a program. I have a bunch of classes all derived from the same base class. I want to loop through a vector of objects, calling a function in each. The problem is that it doesn't matter which class the objects are, only the function defined in the base class is called.
I simplified the code as far as possible to replicate the problem. As you see, I would like a mix of numbers 1,2,3 as the output, however using the vector the only number output is 1. Here is a copy of the output by the way:
I suspect this is the "slice" problem, because the vector is defined with pointers to the base class so it uses the base class functions? The question is how to get around it? How can I loop through a vector of objects sharing the same base class but calling each by their correct member functions?
Code: #include <iostream> #include <vector> class Base { public: int num() { return 1;}
Essentially, the 'Sequence' below uses linked lists to store data. If 'result' refers to the same sequence as 'seq1' or 'seq2', I want 'result' to refer to a new sequence. This new sequence can be default constructed (no copy of 'seq1' or 'seq2' is required). I can't seem to do this correctly. Also, the prototype of the function cannot be altered.
void fun(const Sequence& seq1, const Sequence& seq2, Sequence& result) { // Check for reference to same sequence. If they are the same, // create new sequence for 'result' to refer to if ((&seq1 == &result) || (&seq2 == &result)) {
I am trying to use std::sort to sort a vector of complex objects using a custom function. However, it keeps erroring "Unresolved overloaded function type".
encounter::encounter(){ // ... cut std::sort (allpeople.begin(), allpeople.end(), sortByInit);} bool encounter::sortByInit (character& a, character& b) { if (a.getinit () == b.getinit ()) {
error C3867: 'WordParsor::Form1::PutUpfrmIO': function call missing argument list; use '&WordParsor::Form1::PutUpfrmIO' to create a pointer to memberc:userskingc++wordparsorwordparsorForm1.h... and the suggestion fix generate another error.
One person suggested the gcroot<> object wrapper... but I do not know how to modify/declair the function or its argument type.
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 have no error compiling, but running my project it stops before entering a function and debugging I have an error about Segmentation fault. The function:
I have no error compiling, but running my project it stops before entering a function and debugging I have an error about Segmentation fault. The function:
Code:
Mat logGabor(matriz filter,Mat filter,double r_o,double theta_o,double sigma_theta, matriz radius,matriz theta,int cols,int rows,double sigma_r,int *padSize){ Mat rpad; int k=*padSize; printf("Welcome to the function"); //Here the error ...
More info: I created the matriz as : typedef double** matriz; and a createmat function that give back a double** and in this function I allocate space for matriz and works. In the main:
Code: Mat chr-Rpad[4][5]; //chrOrient=4;chrScales=5 for(int i_or=1;i_or<chrOrient;i_or++){ for(int i_sc=1;i_sc<chrScales;i_sc++){ //some math calculation chrRpad[i_or-1][i_sc-1]=abs(logGabor(filter,imftt2,r_o,theta_o,sigma_theta,radius,theta,cols,rows,sigma_r,padSize));
