I have code already and am looking to incorporate something new into it. I am trying to specify a bit size. A snippet of something similar I have is,
Code:
//header.h
int x; Code: //main.cpp
int func1(int a) {
x = a;
}
Is there anyway I can recast the variable x into another type? For example, if func2 had a char parameter instead, can I somehow make x become char type?
How to change an enum type variable to a string type variable?
View 2 Replies View RelatedI would like to convert a float or double variable into unsigned char variable and back.
float number_float = 23.453f;
unsigned char* number_char = (unsigned char*)malloc(sizeof(float));
number_char = reinterpret_cast<unsigned char*> (&number_float);
float* number_float_0 = reinterpret_cast<float*>(&number_char);
I am not getting the same value back.. why?
I'm attempting to pass a couple of variables over to my Item.cpp class, that is description and item_price. However under item.set(description,item_price), i get three errors. One under the . (period) saying : expected an identifier and two more under description and item_price stating that variable " xxx " is not a type name.
Main.cpp
#include <iostream>
#include "item.h"
using namespace std;
using namespace items;
int main(){
int n;
[Code] .....
I just compiled some code I've been working on at a different OS/compiler and realised that Code: sizeof(unsigned long) returns 4 in one pc and 8 in another.
I've heard that bytesize conventions for basic variables were not particularly "universal" before but this is the 1st time I've had a problem with it.
how do I make a typedef that clearly indicates to whatever compiler compiler I want u32 to be an 32bits unsigned and u64 to be 64bits?
I have two char variables, m_GPSOffset[13] and m_FileName[100]. When m_GPSOffset has a value assigned to it, say for instance +11:25:30. The first entry of the value, in this case +, is always stored in m_FileName. I am clueless on why this is occurring.
View 15 Replies View RelatedI'm a basic C++ programmer, and I am stuck on this problem. You work for a company that collects a set of numbers. The numbers are located in a data file named "./Data_File". The data file contains two columns. how do you count a certain number on the left column.
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <iomanip>
using namespace std;
#define DATA_FILE1 "./Data_File"
#define SUCEESS 0
#define FAIL 1
[code].....
The code below is supposed to be a program that allows the user to enter in 2 matrices and add them together, and gives an error when they're not the same dimensions.
The error I'm getting is on line 11 of MAIN.CPP and is saying "The Variable has incomplete type 'Matrix'".
MAIN.CPP
#include <iostream>
#include <vector>
#include <string>
#include "Matrix Class Input.h"
using namespace std;
int main() {
Matrix A,B,C;
int r,c=0;
[Code] .....
for ex: say i'm declaring two variables under int type and some 3 under char,my output should be lyk this: 2 variables in int and 3 var of type char...(input to the main program is actually another program where these 2 int and 3 char are defined).
View 1 Replies View RelatedWhat is wrong with assigning a reference variable to another reference variable of the same type? I guess I have not understood references very well.
1- In below code, the initialization list gets error because agent "object reference variable" cannot be initialized with a reference variable of the same type.
Code:
class Intention {
public:
Intention(Agent& agent,int Id, string name);
[Code] ....
In other places I have the same problem. In below code the assignment gets error (no overloaded function for assigning a reference to another reference?)
Code:
void Agent::setWorld(World& world) {
this->world = world;
}
//Note: this->world has a type of World&
2- In this other one, I want to assign reference of a vector member to a reference variable of the same type.
Code:
vector<Intention> intentions;
...
Intention& currentIntention = intentions[intentionsIterator]
Okay, I've been working on this Texture class that's going to be compatible with both SDL and OpenGL with the capability to create an array of textures within one class as opposed to multiple classes and such.
Now I've run into a slight issue if I want to return the value of a texture. There's two different types of textures: SDL_Texture, and a standard GLuint Texture. The problem I have is that one or the other is used, not both which is depending on whether or not the person is using OpenGL.
So when the user wants to get the texture, I need the ability to return either an SDL_Texture, or GLuint depending on whether or not OpenGL is being used.
I tried this with a template class, but it didn't work, but I'll post the code so you can see what I'm trying to do.
template <class Tex> Tex Texture::GetTexture(int TextureNumber)
{
if (TextureNumber > NumTextures || TextureNumber < 0)
return;
[Code]....
It basically just comes down to the last four lines of code. If the person is Using OpenGL return a GLuint, if the person is using SDL, return an SDL_Texture.
I would prefer to have the GetTexture function to be one function instead of two separate ones so I don't have to call a different function every time to check if I'm using SDL or OpenGL.
Can I create 1 variable that accept any type? And can I give it the NULL value too?
View 14 Replies View Relatedis there any variable type(or with another keyword) that we can change it's value in global scope?
View 5 Replies View RelatedA 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'm fairly new to C++ and have begun working with pointers. I wish to create am array called sigmaf_point that reads data from a text file. I have managed to get that working, but when it comes to using this pointer I come across some problems. The array is created as such:
Code:
double sigma [5];
double *sigmaf_point = sigma;
void read(double *&sigmaf_point)
string s;
ifstream Dfile;
std::stringstream out;
[Code] .....
I then create a coordinate system inside the main file, as the program I am writing is about modelling the movement of atoms, which requires you to know the coordinates:
Code:
int main();
double **coords_fluid = new double*[5000];
for (int i = 0; i < n_atoms_methane; i++) {
coords_fluid[i] = new double[4];
}
Now, the problem arises when I want to calculate a new variable as so:
Code:
for (int i = 0; i <= n_atoms-1; i++) {
sf1=sigmaf_point(coords_fluid[i][3]);
}
I get the error C2064: term does not evaluate to a function taking 1 arguments, and a red line under sigmaf_point that says it must be pointer to function type. I am a bit confused about this.
I am trying to set a variable of type char equal to an element in an array of characters. For example:
char data[4] = "x+1";
char element;
element = data[2];
This seems like a logical progression from number arrays, but when I print both element and data[2], I get data[2] as expected, but element gives a different character every time (I assume a garbage value).
How I can implement it.
Tickable.h
#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 getting a compilation error from the code below. It is when i am naming a variable with my user defined type.
#include<iostream>
#include<cstring>
#include<cstdlib>
using namespace std;
class person {
[Code] .....
C:Dev-CppTRIAL.PASS.!!!.cpp In function `int main()':
66 C:Dev-CppTRIAL.PASS.!!!.cpp expected primary-expression before "p"
66 C:Dev-CppTRIAL.PASS.!!!.cpp expected `;' before "p"
74 C:Dev-CppTRIAL.PASS.!!!.cpp `p' undeclared (first use this function)
(Each undeclared identifier is reported only once for each function it appears in.)
83 C:Dev-CppTRIAL.PASS.!!!.cpp `X' undeclared (first use this function)
My intent was to convert the string variable for the year to an integer data type. The code compiles but now cannot run on my system. I'm not sure what's going as to what the program is displaying.
Objective: Prompt the user for two years. Print all Comedy movies that were released between those two years.
#include <iostream>
#include <cstdlib>
#include <string>
#include <fstream>
#include <cctype>
using namespace std;
struct Movie {
string name;
[Code] .....
If I have a pointer variable indicating memory location in which we have stored what user entered and the pointer is of type volatile if the user gives the character 'a' twice , then this character will not be fetched twice from the memory but only when the character is changed???
This is the one meaning of the volatile? the other is that the value will be changed without the program itself change it?
How can i write a function that will read an "unsigned integer" into a variable of type "unsigned short int"? i can not use cin >> inside the function.. so i am looking for atleast a hint!
View 16 Replies View RelatedI'm having some problems with changing an array of numbers of type char to type int. Every time i try to sum 2 array indexed values it returns some letter or symbol. Also, if i change the type of the array in the functions the compiler gives me an error message. I would also like to add that the problem requires that the first two arrays be char so each individual number gets assigned to a different value.
My current code is:
Code:
#include <iostream>
void input(char a[], char b[], int& size_a, int& size_b);
void convert(char a[], int size);
void reverse(char a[], int size);
void add(char a[], char b[], int c[], int size);
int main()
[Code]....
how to convert an element of int type of an array to char type?
View 2 Replies View RelatedI have a function like this:
template<typename T>
void f() {
//...
[Code]....
list contains, in order: A, B and C in any order, D, E
I am thinking it is possible with some clever template and polymorphism combos, but maybe not. As a last resort I know how to make it work by storing static type information in each class, but I'd like to avoid that if possible.
I need to use the type RectangleF as a built in type in c++ ie I need to declare a variable rect as RectangleF rect;
what do I have to include to be able to do this.
I am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.