In a function, I have a static variable that I want to assign the time in seconds when a certain condition is met and keep that value until a different condition is met. The time value is a struct. Since now->sec is always incrementing, will timeWhenEventMadeActive below hold onto the initial value or will it increment every time the function is called? I cant seem to test this.
static time_t timeWhenEventMadeActive = 0;
static bool initTime = 0;
if (!initTime) {
timeWhenEventMadeActive = now->sec; //holds uptime value in seconds
struct Speaker { static int numElem; string name; int number; // Phone string topic; float fee; };
// IN main() FUNCTION Speaker s[10];
The goal is for numElem to keep track of how many of the 10 elements are in use. However, I'm not sure the proper way to access the element, if it's even possible.
#include<iostream> #include<ctime> #include<boost/progress.hpp> using namespace std; class parent { public: virtual void dynamic_display(){
[Code] ....
I am getting the following as output
Calculating....Static Function is called1times The number of processor clicks is0time is0 Calculating....Dynamic function is called1times The number of processor clicks is0time is0 Static Function is called2times Dynamic function is called2times Static Function is called3times Dynamic function is called3times
I am actually trying to calculate the time to execute a statically binding method and a dynamically binded one.consider only the first four lines in my output. Why am i not getting the actual result.
I was exploring static variable by writing code snippets. I tried below code and it ended up throwing error saying "error: storage class specified for parameter 'b'"
Why static cannot be used in func() ?
Code: int main() { int a; a=5; func(a); printf("%d",a); return 0; }
If i declare 2 variables like this static int first, second; will both of them be declared static or will only first be declared static and second a regular variable?
I need to keep a static variable in a member function of a class that I have many objects of. I've had some trouble with it, and when I read up I found that such variables are static across all instances. Is there any way around this?
What is the problem with the following code is? It compiles with Visual C++ 2012 but does not with g++:
//a.h
#ifndef Loaded #define Loaded using namespace std; class MyClass{ public: static const int MyStaticValue = 200;
[Code] ....
If I try to compile this using the command
g++ a.cpp b.cpp
I get an "undefined reference to 'MyClass::MyStaticValue'" error for the line "A = MyClass::MyStaticValue;" in main(). The strange thing is that if I change the line to "A = (int) MyClass::MyStaticValue;" it works fine and the output is
200 200
as expected.
The code also compiles under g++ if I move the defintion of MyStaticValue from a.h to a.cpp by const int MyClass::MyStaticValue = 200;
I try to create small project in order to better understand how key word static works with templates . However some compiles errors crush my plan.
1>------ Build started: Project: 4.2b - Ex 1. Static Variable for Array Def Size. Templates, Configuration: Release Win32 ------ 1> main.cpp 1>c:all myс++ha level 6solution level 6solution level 64.2b - ex1. static variable for array def size. templatesarray.cpp(40): error C2724: 'Array<Type>:efaultSize' : 'static' should not be used on member functions defined at file scope
Would each instance of Foo create a new counter variable, or would it remain the same for all of them, i.e. baz.funky() would always use the same counter variable? What if the class was a template?
Doesn't it allocate the class static variable to the heap, thus executing its algorithm then destroying it when the program ends - or. What exactly does it tell me? When the static variable is initialized, it takes place first before any of my other functions?
A have two classes, one inheriting the other, and the parent class being abstract (I plan on adding more child classes in the future). For reasons I won't bother mentioning, I'm making use of an STL container as a way for me to access all of the child objects in the heap. I've done so by making use of a map, with key type int and value type being a pointer to the parent class:
//PARENT.H class Parent { protected: static int n; static std::map<int, Parent*> map; public: virtual void pureVirtual() = 0;
[code]....
The Problem:In line 5 of Parent.cpp, initializing the value of the element to new Child won't work, as according to the compiler, the Child class hasn't been declared yet, and including Child.h into the Parent.h only opens an even bigger can of worms.I also can't initialize it as new Parent, seeing as the parent class is an abstract one.
The Question:Is there a way I can initialize the static map properly. Making the Parent class abstract is not an option.
I am having trouble getting the cout statements that I commented out to work properly. And I can't figure out why the first movie in the movies.txt file displays at the end of the list in my output screen when it should only display once as the first item. I am also having trouble figuring out where and how to set up the static variable.
Purpose : This assignment requires that you to develop a program using the classes listed above. Specifically you will build a hash table containing movie data. The collision strategy will be to build linked lists as the array elements.
Program Specifications : Your program will read the data from the file named Movies.txt located in the StudentFiles1.zip file on the Connections Portal. Each record contains 2 fields separated by a space. They are:
FieldsData Type Motion Picture Association Code (MPAC)Integer Movie NameString
Your application program will read each record, create a Movie structure instance and place that structure instance into the hash table.
You will need to modify the appropriate code to provide for an audit trail of the hash table construction. To accomplish this, you will use cout statements in the above class member functions. You will need to modify them to include couts, but the modifications will be relatively small. If not, you are doing it wrong. The hashing algorithm to use is:
Index = int ( 0.618033 * MPAC) % size
Make the array size a constant and set it to 10.
Include a counter for the number of collisions that occurred in building the hash table. Including a static variable in the LinkedList or List class is the best method for doing that.
See the sample audit trail below for the first 5 records on Movies.txt and the size of the hash table set to 3. This is shown for illustration only. The full file will have different locations calculated.
1101-Casablanca is being added The hashed location is 2 There was no collision loading 1101-Casablanca ------------------------------------------------ 1200-Duck Soup is being added The hashed location is 0 There was no collision loading 1200-Duck Soup ------------------------------------------------
[Code] ....
After the above is displayed, prompt the user to enter the MPAC of a movie to locate. Produce an audit trail when locating the requested movie as shown below: Make sure you list all movies that have collided at the hashed location. That may also cause you to modify one of the existing ADTs a little.
Will search for 6601 at the hashed location is 2 There was a collision here with 6601-Wizard of Oz There was a collision here with 1101-Casablanca retrieved from hash table: 6601-Wizard of Oz
#include <list> #ifdef TICKABLE_EXPORTS //Automatically defined by MSVS #define DLL __declspec(dllexport) #else #define DLL __declspec(dllimport) #pragma comment(lib, "Tickable.lib") #endif
class DLL Tickable{
[Code] ....
error LNK2001: unresolved external symbol "private: static class std::list<class Tickable*,SKIPPED BITS> Tickable::subs" HUGE_SYMBOL_LIST PATHTickable.obj
I know with such a tiny and insignificant class the dll export seems pointless but this class is actually intended to be a .lib ONLY. But it is derived from by .dll style classes, and through inheritance this error is the exact same as what appears in the derived class, I just imagine that the cut down version would be easier to work with.
Is it possible to hold either a static variable in a dll which is of a dynamic type, OR would it be possible to reference an external variable which is static throughout the instances and this variable can be chucked away in a namespace of mine somewhere?
I suppose my only other option (if this is possible) would be to define a maximum instance number and create a standard array of pointers but this could both waste so much memory when not in use and cause problems if I need more memory.
I am modifying a set of static variables inside of the class's member function. The static variables are private. An example of what I'm doing is as below,
utilities.h ----------- class utilities { private: static int num_nodes;
public: void parse_details(char* );
[Code] ....
I get a compilation error in the function void utilities::parse_details(char* filename)
which says: undefined reference to `utilities::num_nodes'
Code: typedef struct _a { int id; } a; typedef struct _b { a my_a; my_a.id = 1; // error: expected specifier-qualifier-list before "my_a" } b;
I get error: expected specifier-qualifier-list before "my_a"
I must set the id for the kind of struct created inside the struct def because main() will be casting based on this id. Thats how I will know which structure b contains by it's id, there could be hundards of different structs with different values I will cast to the correct one and know it's members by it's id. How do I ?
The definition of the struct doesn't show it but the documentation says that bRawData is variable length. sizeof(RAWINPUT) will not be the correct size when the data field is of RAWHID type so how do you allocate a variable with automatic storage type that has the right size for the entire struct? You can get a header that has the size for the entire struct but how do you actually allocate storage space for the data without using malloc? I've seen some example code that used a char array but that violates aliasing rules and there are also alignment issues with that approach.
at my work we use a static analysis tool and it is pointing out some uninitialized variables. One of which is a class member variable which is a C struct. Now, that variable is already declared in the header file for the class.
