C++ :: Proper Way To Define A Variable Type
Sep 17, 2013
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?
View 12 Replies
ADVERTISEMENT
Feb 5, 2014
I am currently working with the fundamental types in C++, and there is some ambiguity (which I have tried to solve).
I am creating a function that needs an overload for _all_ fundamental types (in addition to a void *).
Some types overlap (like "unsigned wchar_t" and unsigned int, whilst wchar_t never overlaps), so, I would like some confirmation about my current overloads being complete and overlap-free on your system as well.
bool
char
unsigned char
signed char
wchar_t
char16_t // In fact, builtin-types, look like typedef.
char32_t
[Code] ....
To test the valid types, I have created a small test that shows which builtin types overlap and which do not.
#include <map>
#include <vector>
#include <iostream>
#include <string>
#include <typeinfo>
int main(int argc, char *argv[]) {
[Code] ....
I also wonder; what "type" is nullptr? I tried googling but no definitive answers came up. Still, it works as a valid function overload.
View 3 Replies
View Related
Aug 10, 2014
How to change an enum type variable to a string type variable?
View 2 Replies
View Related
Apr 29, 2014
Define a class for a type called CounterType. An object of this type is used to count things, so it records a count that is a non-negative whole number.
Include a mutator function that sets the counter to a count given as an argument. Include member functions to increase the count by one and to decrease the count by one. Be sure that no member function allows the value of the counter to become negative.Also, include a member function that returns the current count value and one that outputs the count. Embed your class definition in a test program and run sufficient tests to verify it all works correctly.
View 1 Replies
View Related
Jan 18, 2015
How can I define type MARKS which will be able to hold 4 elements just like array? I want to access it just like normal array elements using brackets []. In the following struct I want to use such type.
Code:
typedef struct {
MARKS ** pointers;
} ARGUMENTS
void main(){
ARGUMENTS arguments;
[Code] ......
Purpose of the struct ARGUMENTS is to hold 4 pointers to string. I want to mark few positions in string so I can simple access them. E.g. name=John
Code:
arguments[0][0]=0; // begin of the param name
arguments[0][1]=3; // end of the param name
arguments[0][2]=5; // begin of the value
arguments[0][3]=8; // end of the value I mean not to save int but the pointer to the corresponding position.
View 8 Replies
View Related
Aug 31, 2013
I want to define variable that is in HEX value & has 64 bits.but I dont know what I can use.....I use unsigned long long but it doesn't useful.
View 2 Replies
View Related
Mar 21, 2013
I program unix sokcet programming , and part of my code is ti open file from server and open it , but i surprised with this wierd error i dont have any reason for it ?
Code:
#include <errno.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
[Code] ....
File name is : myHeader.h
myHeader.h:24:1: error: unknown type name "File"???
View 1 Replies
View Related
Apr 29, 2014
Define a class for a type called CounterType. An object of this type is used to count things, so it records a count that is a non-negative whole number.
Include a mutator function that sets the counter to a count given as an argument. Include member functions to increase the count by one and to decrease the count by one.
Be sure that no member function allows the value of the counter to become negative.
Also, include a member function that returns the current count value and one that outputs the count. Embed your class definition in a test program and run sufficient tests to verify it all works correctly.
View 3 Replies
View Related
Aug 28, 2014
I have looked into this and I've also read that I should be able to Config Each column Accordingly.
I'm Currently using this piece of code:
//Change the Headers on the DataGridView2//
dataGridView2.Columns["cashQTY"].HeaderText = "QTY";
dataGridView2.Columns["cashDescription"].HeaderText = "DESCRIPTION";
dataGridView2.Columns["cashSupplier"].HeaderText = "SUPPLIER";
[Code] ....
Currently it does not error, but it also does not Show the DateTime in the GridView when running either..
View 2 Replies
View Related
Aug 15, 2013
I want to write encryption algorithm.first af all I need to define variable( binary input ) that it is 256 bit but I dont know what should I use...then I want to XOR this to variable ( a & b ) ( each of them is 256 bit)
View 6 Replies
View Related
Aug 17, 2014
I have to create a program that read two numbers and the math operators +, -, * and /. After that I should print the operation required. But I tried to declare a <symbol> variable as char type, without sucess...
Here goes my script:
float num1, num2, result;
char symbol;
printf("Write two numbers:
");
[code]....
View 1 Replies
View Related
May 10, 2013
I 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?
View 2 Replies
View Related
Feb 8, 2015
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] .....
View 11 Replies
View Related
Jul 24, 2014
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?
View 8 Replies
View Related
Jun 12, 2013
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 Related
Apr 23, 2013
I'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].....
View 1 Replies
View Related
Apr 18, 2015
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] .....
View 5 Replies
View Related
Jul 25, 2012
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 Related
Jun 4, 2012
What 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]
View 6 Replies
View Related
May 2, 2013
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.
View 4 Replies
View Related
Aug 24, 2013
Can I create 1 variable that accept any type? And can I give it the NULL value too?
View 14 Replies
View Related
Nov 17, 2013
is there any variable type(or with another keyword) that we can change it's value in global scope?
View 5 Replies
View Related
Dec 3, 2014
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.
View 3 Replies
View Related
Nov 22, 2012
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.
View 3 Replies
View Related
Mar 3, 2014
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).
View 5 Replies
View Related
Oct 15, 2013
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.
View 5 Replies
View Related
