I have recently found this article: URL.....In their example, by declaring variables in other order, they saved 8 bytes. However, shouldn't compiler take care of it? Is it true, and should I declare variables more carefully?
View 3 RepliesIn my program I am supposed to call isEqualTo with a user defined class type, and print out if my two numbers being compared are equal or not. I had to write two versions of this, one with just a template which works fine, but when I implemented the class, all the sudden my program just spews out true no matter if actually equal or not. Here is what I have so far:
#include "stdafx.h"
#include <iostream>
#include "UserClass.h"
using namespace std;
template<typename T>
bool isEqualTo(T value1, T value2){
if (value1 == value2)
[Code] ....
I am trying to make a menu program and was wondering if there is a way to declare something more than once without using a different word.
ex.
#include <iostream>
using namespace std;
double grams, ounces, inches, feet, meters; //units to convert
int choice; //menu choice
int main() {
cout << "Welcome to Measurement Converter" << endl;
[Code] .....
I dont really know how to explain it but im trying to use int choice to make choose a program from a simple list.
I would like to know the difference between the following two forms of array declaration:
(1)double myArray[3] = {1.0, 2.0, 3.0};
(2)array<double,3> myArray = {1.0, 2.0, 3.0};
If I say the second one allows to use different functions like .begin(), am I right? Is there any other difference between these two declaration?
Can we use using declaration within name space scope? is it safe to use it?
I think we can use using declaration for class scope and function scope only.
I am trying to understand the behavior of following code. Basically how does printf() prints the value rather than address.
Does initializing value to a pointer during declaration makes a difference when assigned from a variable?
Code:
1 #include <stdio.h>
2
3 int main() {
4 const char *var1 = 'A';
5 int *vint = 10;
[Code] ....
I read that Memory is allocated during definition of a variable and not during declaration. Declaration is something like,
Code: int x;
And definition is assigning some value to it. This is what my professor taught. My doubt is if memory is not allocated during declaration, then how the compiler successfully compiles and runs the following, which i had already tried.
Code:
#include<stdio.h>
#include<conio.h>
int main() {
int c;
int *p=&c;
printf("%x",p);
getch();
return 0;
}
The variable c is only declared. But the program outputs a memory address. Shouldn't it show an error?
I've included <cstddef> into a project of mine in favour of <stddef.h>. When I tried to compile my project, I get 50+ errors stating that types such as "::size_t", "::div_t" and "::abort( )" have not been declared even though <cstddef> includes <stddef.h>.
I've tried searching both the global namespace and the standard namespace, but neither way works. At this moment in time, I don't have any compiler options enabled that may affect the way identifiers are defined, C++11 isn't enabled (which doesn't affect the <cstddef> header anyway), the project is a C++ project, and I've tried using the plain old <stddef.h> header, but the problems still persist.
I'm using GNU's C++ compiler ("__GNUG__" is defined).
What is the difference between:
const int testFunction() &
int testFunction() const
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?
View 5 Replies View RelatedI've got some problems with the declaration of a bitset container in my class
I've got a class A and want to have a bitset container in it, whose size just get's defined when running an instance of this class:
#include <bitset>
class A {
bitset <n> bc;
A(int n) : n(n) {};
};
Something like that.
I want to understand the ways in which arrays can be declared and used. What each of the following do or what's the difference between them and what would be the length of each:-
1 - char ary1[50];
2 - char ary2[50] = {'H','e','l','l','o'};
3 - char ary3[50] = {'H','e','l','l','o',' '};
4 - char ary4[50] = {' '};
5 - char ary5[50] = {' ','H','e','l','l','o'};
6 - char ary6[50] = {' ','H','e','l','l','o',' '};
#include<iostream>
#include<conio.h>
#include<string>
using namespace std;
class ir;
class Bank_acc {
private:
string name,type,s;
long int accno,temp,balance,in;
[Code]....
errors are:
|6|error: forward declaration of 'class ir'|
|54|error: invalid use of incomplete type 'class ir'|
|99|error: no matching function for call to 'ir::interest()'|
Code:
struct foo {
char label[64];
int state;
} bar[3] = { };
Will the above code ALWAYS initialize to 0 all objects:
bar[0].label
bar[0].state
bar[1].label
bar[1].state
bar[2].label
bar[2].state
Using gcc and g++, it does in my testing But was wondering if it can be unsafe under some circumstances.
I even tried without = { } and it is still initialized to 0 for all objects!
I want to access the body of the Add() of a list in c# to see how it works, but it only just gives me the declaration.
[DebuggerTypeProxy(typeof (Mscorlib_CollectionDebugView<>))]
[DebuggerDisplay("Count = {Count}")]
[Serializable]
public class List<T> : IList<T>, ICollection<T>, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>, IEnumerable<T>, IEnumerable {
public void Add(T item); // thats all. I tried go to declaration but still gives me this line of code. This is from metadata in Visual studio.
}
How this thing work. It just a declaration not a definition yet its still doing something. How is that possible.
I have a class "SelectionGroup" which derives from a class "RMFObjectContainer". RMFObjectContainer has member variables of type SelectionGroup, so I need to include SelectionGroup.h in the header of RMFObjectContainer.h.
However, since SelectionGroup needs RMFObjectContainer to derive from it, I get a typical case of mutual inclusion.
I then proceeded to put the forward declaration
class RMFObjectContainer;
instead of
#include "RMFObjectContainer.h"
into the header of SelectionGroup.h.
However, I receive the following compile error (MSVC2010), as if the forward declaration was unseen:
#pragma once
#include "Solid.h"
#include "Entity.h"
#include "SelectionGroup.h"
[Code]....
is possible to combine structures declaration and definition in programming language?
View 3 Replies View RelatedAny difference between
Code:
class SomeOtherClass;
void foo(SomeOtherClass* p);
And
Code:
void foo(class SomeOtherClass* p);
I was told that "2" would limit the scope of the forward declaration to the declaration of foo... However, after testing it, it appears that both behave the same...
I keep getting a "Declaration syntax error" at line ""int main()". Is there something wrong with my int main()? And how do I go about it? Here is the program:
#include<stdlib.h>
#include<iostream.h>
#include<stdio.h>
#include<math.h>
#include<conio.h>
float rung4(float x, float y, float h)
int main() {
float eps=0.00001;
[Code] .....
I would like to write a program that prompts the user to enter a series of client names which the program will then store in an array of structures. I'm thinking something along the lines of:
struct sInfo {
vector<string> vName;
float fClientHoldings;
};
sInfo sClientData[100]; //create an array of structures for up to 100 client's
sClientData[0].vName="Acme"; //these will be inputted by the user in my program, but I've attempted to initialize them here for simplification
sClientData[1].vName="Enron";
I can't declare a structure array after I declare it. Is this true? If so, is there an alternate approach that I should be using?
I have a little program that does some statistical processing on text files. The program has thrown a segmentation fault with an input file that is larger that I have used before. I didn't write this tool, so I went searching for the problem. Data from the input file is dumped into a 2D array and the program fails at the declaration of that array.
Code : double A[cont][Nr_col_split];
The vales for cont and Nr_col_split and determined from the input file and in this case, cont=807 and Nr_col_split=350. I assume that these values are just too large and not enough memory can be allocated, or something like that. Do I need to use reserve or similar to set aside enough memory? I will have input files that are quite a bit bigger than this one, so perhaps there needs to be a different solution for storing the input file data.
I was going through a code where i found the definition of int array[63] in one of the source files. But i also found the declaration as extern int array[66] in another source file. This is clearly wrong, but my doubt is how the compiler compiled it. It should have thrown error. In case if it compiles then what will be the behavior of the system? Will it be normal or some undefined behavior?
View 3 Replies View RelatedWhy I take warning on this code :
Code:
#include<stdio.h>
extern int v = 0; // Declaration and definition of an external
int main(void)
[code]...
Is there any error? Why I take a warning: 'v' initialized and declared 'extern'|||=== Build finished: 0 errors, 1 warnings ===| ???
and what is the meaning of :An extern declaration that initializes a variable serves as a definition of the variable. This rule prevents multiple extern declarations from initializing a variable in different ways.
I have some files:
file1: 1000x500 array of numbers
file2: 2000x600
file3: 300x5000
...
I would like to automatically declare array variables of myarray1, myarray2, myarray3... that reads the numbers from files:
Code:
for (i1=0; i1<nrows; i1++)
{
for (i2=0; i2<ncolumns; i2++)
{
fscanf(filename, "%lf", &y);
myarrayX[i1][i2]=y;
}
}
nrows and ncolumns can be passed from a config file. Also I can cat all files into a single filename. However, the difficult part is:
How to declare different myarrayX automatically ? (A workaround is to declare a huge 3d array but I do not want to do this).
class intClass{};
class stringClass{};
template <typename T>
class Mediator {
// bunch of code
};
I want Mediator<int> to declare intClass friend, Mediator<std::string> to declare stringClass friend etc..., without having to redefine the entire specialization
template<>
Mediator<int>::friend intClass;
PROGRAM:-
#include<fstream.h> //for reading and writing files
#include<conio.h> //for clrscr()
#include<string.h> //for string characters
#include<stdio.h> //for gets and puts function
#include<process.h> //for exit function
#include<iomanip.h> //for setw function
#include<dos.h> //for delay and sleep function
void main()
{ char ch,c=0,che=16;
int i=1,j=16;
[Code] .....