If I have a struct of some vector members, like
struct {
vector<double> a;
vector<double> b;
vector<double> c;
// ...... continue
} struct_test
How can I assign a value (push_back()) to all the vector members simultaneously, instead of do it one by one?
Suppose I have a struct with 20 members. I want to assign each of those structs with values. Instead of accesing by explicit convention, i.e.:
Code: struct.member1 = 1;
struct.member2 = 2;
...
...
...
struct.member20 = 6;
Is there any way to encapsulate it in a for loop and use an iterator variable to indicate the member? i.e.:
Code: for (int i = 0; i < 20; i++)
struct.i = i;
The above is pseudocode but Im sure you get what Im trying to do?
I am trying to pass multiple args to g_signal_connect through a struct and it's members. I think the problem lies with execlp. I am trying to pass the struct members to it but I keep getting errors. No matter how I format execlp and the struct args, I always get an error. The current error I receive is Bad address. Like I have said before, no matter how I format execlp, I receive some sort of error.
Code: /*
Compile me with:
gcc -Wall sshfs-gtk -o sshfs-gtk `pkg-config --cflags --libs gtk+-2.0`
*/
#include <gtk/gtk.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <wchar.h>
static void destroy( GtkWidget *widget, gpointer data ) {
[Code] .....
I've been reading the tutorials on Friendship and Inheritance [URL] ..... but I still don't understand why I can't access members of the same struct type.
bool wordBeginsAt (int pos) {
if (pos == 0)
return true;
///use the 'message' string
Message go;
return isAlphanumeric(go.messageText[pos]) && (!isAlphanumeric(go.messageText[pos-1]));
}
The code above is located in a source file, where the function isAlphanumeric passes a char value, and Message is the struct containing the string I want to access. Below is the declaration of the struct and string located in the corresponding header file.
struct Message{
.
.
.
private:
std::string messageText;
};
My frustration comes when I try to call and assign messageText like the tutorial does to its private members, but I keep getting an error saying I can't access the string because it is a private member. Is there a way to access the string without having to pass it through the function wordBeginsAt?
I'm a C beginner trying to assign struct member values to other struct members to create a list.
I've tried dot notation, pointer notation, strcpy, memcpy, memmove and normal assignment.
Nothing has worked.
cust_list.h
#include <iostream>
using namespace std;
struct box{
[Code].....
C++Dev.cpp:23: error: incompatible types in assignment of ‘const char [15]’ to ‘char [40]’
I need to create a list of all members of a struct using the sturct definition as input. The struct is NOT part of the program, but is the input to the program.
The struct that I am using changes over time as features are added. I need the complete, fully qualified field names to then generate a table with all names with their offsets, type and length.
This information then allows me to create readers of the data that will run on different architectures, compilers and operating systems.
The struct currently has 800+ lines and uses typedef and embedded structs.
Perhaps this could be done creating LEX, YACC, Perl, SED, AWK or other language system.
I was wondering why, in C, the sizeof of a struct is larger than the the sum of all the sizeofs of it's members. It only seems to be by a few bytes, but as a bit of a perfectionist I fine this a bit annoying.
View 1 Replies View RelatedIs there a way to simultaneously update two variables, like in Python?
For example
Code: x, y = 0, 1
x, y = y, x + y
I would like to create N matrices of dimension (n,k) simultaneously. Lets say for example that N=3. I read the command a[n][k][N] but I don't understand how to use it.
I know that for some of you this question is silly but I' m new to this language and I have noone else to ask.
I would like to create N matrices of dimension (n,k) simultaneously. Lets say for example that N=3.
I read the command a[n][k][N] but I don't understand how to use it.
I have two or more printers and one computer. I want to print to both printers the same document at the same time... Thus when I press print on my document both printers will print the file simultaneously.
View 6 Replies View Related#include <stdio.h>
#define MAX_USERS 20
struct {
char ID[10];
char Name[40];
int Pos;
[Code] .....
I was attempting something weired with address to move data around when I discovered that the size of the array is not what I expected. I am passing this structure as &Users to a function that declares it as a void *, then I can deal with chunks of data (memmove) and not have to worry about index or things like that. However...sizeof is returning something I do not understand.
Im having trouble creating a struct within a struct node. the program suppose to hold students firstname, lastname, and gpa in a node therefore creating my linked list. Line 26 keeps saying that cannot convert parameter 2 from 'studentType to std::string
#include <iostream>
#include <string>
using namespace std;
struct studentType{
string firstname;
string lastname;
double gpa;
[code].....
This is a function that is supposed to add two different arrays containing 9 items together, but it has a problem when it comes to doing any actual adding.
Code:
int * add_data(int x[], int y[], int z[])
{
int i;
char a[9];
for (i=1;i!=9;i++)
{
printf("%d =x
", x[1]+y[1]);
x[1] + y[1]= a[1];
}
return a;
}
I am new to c++ programming and i have written a simple class program to display the name and duration of the project
#include<iostream>
class project {
public:
std::string name;
int duration;
};
[Code] ....
Now i am trying to the write the same program with the usage of member functions using set and get member functions. i have tried the following
#include<iostream.h>
class project {
std::string name;
int duration;
// Member functions declaration
[Code] ....
I am not sure whether above code logic is correct, how to proceed with it.
How to access the name and file name members on line 42 and 43?
Code:
typedef struct {
char * name;
char * filename;
} FILES;
FILES * files[256];
}
[code]...
How to access the name and filename from within function?
*files[count].name = chTmp;
I want to define a class, which will have two members, for example, vaporPressureStatus and vaporPressure
enum vpStatus_t {nonesense, unknown, known, saturated};
class pore_t {
public:
vpStatus_t vpStatus;
double vaporPressure;
};
when vpStatus is nonsense and unknown, the vaporPressure should not have a value; and if I calculate out a value for vaporPressure, the vpStatus can be set as known.
I am wondering if there is any set, pair or other structure can hold this two members together, so that when I change one's value, the other guy will also change accordingly.
I am versed in qsorting struct members within a struct instance, as in the example below:
Code:
#include <iostream>
#include <stdlib.h>
using namespace std;
struct item_database {
[Code]....
What I CANT do however is to sort an array of structs by one of its members. This is a complete different problem even if it sounds similar.
In other words, the problem is this; Say we have a struct:
Code:
struct item_database {
int key;
string token;
};
Then we declare an array of this struct in the heap:
Code: item_database *idptr = new item_database[700000]; and initialize its values.
How would one go about sorting this heap array of structs by its member function "token"?
I used the following call to qsort (standard library) and call to the compare function but it doesnt work:
Code:
qsort (idptr, 1000, sizeof(string), compare);
Code: int compare (const void* a, const void* b){
if (*(char*)a >= *(char*)b)
return 1;
else
return -1;
}
Or in more lamens terms say we have the following stuct instances:
Key: Token:
1 Hello
2 World
3 How
4 Are
5 You
Then I need those structs to order according to token (alphabetically, increasing or decreasing depending whats in our compare function).....
files.c
Code:
#include "include/types.h"
#include "include/gaussian.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
[Code]....
I need to access the members .name and .filename to allocate memory and copy strings in there.
Code:
files[count]->name=malloc(64);
files[count]->filename=malloc(64); SIGSEGV error
How to make the reference working?
I've been creating an API and I'm now stuck on callbacks. There are many APIs that allow callbacks to class members(e.g. Windows API) using a void pointer to the object. I've searched the internet for hours and I can't find one example of how to use the "hidden object parameter" of an class method pointer that doesn't use std::function/bind or boost::function/bind. Any information on how API's like Windows API are able to use class methods as callbacks
View 6 Replies View RelatedI've been having a problem concerning the initialization of const static integral members with floating point calculations. I'll let his sample program do the explaining:
class Foo {
public :
Foo() {}
const static int samplerate = 44100;
const static unsigned short tempo = 120;
[Code].....
I know you can't initialize const static non-integral types on the same line on which they're declared, but I don't see why even an implicit cast to an integral type should be disallowed. I make my calculations using doubles, so I'm surprised that even though it should degenerate into an integer - it's still a problem for the compiler.
The reason that class members are private by default is because, in general, an object of a class should be a self-contained entity such that the data that make the object what it is should be encapsulated and only changed under controlled circumstances. Public data members should be very much the exception. As you’ll see a little later in the chapter, though, it’s also possible to place other restrictions on the accessibility of members of a class.
View 17 Replies View RelatedSuppose I have a class "A", which has a method "void AMP_call()" that calls paralel_for_each in which another method, "float amp_function(float) restrict(amp)". When I call that method, can it then use members of "A"?
class A {
void AMP_call();
float amp_function(float) restrict(amp); // do something on a device
float allowed_variable;
std::vector<bool> not_allowed;
[Code] ....
Another way to frame my question, perhaps to make it easier to understand what I am after, would be that I want to know what happens if an amp-restricted method is called where the body of the class itself (which is not amp-compatible and afaik doesn't have to be since it's not passed to the device) may contain members that are not amp-compatible.
All of the msdn blogs I could find deal with which functions and methods can be called from within a parallel_for_each loop, but not with which variables are available to the lambda function itself.
Need a C++ constructor to initialize each members of an array. how to give value for for each elements of an array declared as a class object according to the users input.
View 1 Replies View RelatedWrite a C++ program to implement the following description:
1. Define a global structure and name it GStruct with the following members:
a. X as integer
b. Y as integer.
2. Define a local structure inside the main and name it LStruct with the following members:
a. X as integer
b. Y[3] as GStruct
3. Inside the main declare two variables V1 and V2 of type LStruct.
4. Give values to all of their members by using input statement (cin).
5. If V1 equal V2 print "They are equal" else print "Not Equal".
#include <iostream>
using namespace std;
struct GStruct {
int x;
int y;
};
int main() {
[Code] .....