I'm having trouble figuring out how to find the size of an array program that involves "struct."
#include <iostream>
using namespace std;
struct d{
char* a;
float b;
int c;
[code].....
When I run this program, the output is 80(for my compiler). That would mean that each element in the array is 16 bytes but I don't understand how struct d is 16 bytes.
#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.
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 Relatedtypedef struct Element Element;
struct Element {
char x;
double* y;
[Code] .....
This one with y pointer gives 8
typedef struct Element Element;
struct Element {
char x;
double y;
[Code] ....
This one with a normal y variable gives 12
The WinAPI has a struct like this for raw input:
Code:
typedef struct tagRAWINPUT { RAWINPUTHEADER header;
union {
RAWMOUSE mouse;
RAWKEYBOARD keyboard;
RAWHID hid;
} data;
[code]...
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.
I'd wrote a program to encrypt a message within a bmp file using my own structs and all for everything (yes, call me a ........head) The program works but for some weird ........ing reason I was forced to subtract 2 bytes from the header size to get the correct value. I've narrowed down the issue to my BmpFileHeader struct.
Here's a short program that demonstrates the issue:
Code:
#include <stdio.h>
#include <stdlib.h>
#define BYTE unsigned char
#define WORD unsigned short
#define DWORD unsigned long
#define LONG signed int
[Code] .....
Tried with both gcc and TinyCC and got the same result so it doesent seem to be a compiler bug. Microsoft's structures though are giving the correct size, even though they have the exact same definition.
Microsoft's defines:
Code:
// windef.h
typedef unsigned long DWORD;
typedef unsigned char BYTE;
typedef unsigned short WORD;
[Code] .....
I am not exactly sure how to do this and i keep running into problems. This is my code here that works.
Code:
#include<iostream>
using namespace std;
struct record {
double quiz1;
double quiz2;
double midyear, midyear_one;
[Code] .....
Write a program that will predict the size of a population of organisms. The program should ask the user for the starting number of organisms, their average daily population increase (as a percentage), and the number of days they will multiply. A loop should display the size of the population for each day.
Input Validation: Do not accept a number less than 2 for the starting size of the population. Do not accept a negative number for average daily population increase. Do not accept a number less than 1 for the number of days they will multiply.
My code works fine just up until the end.
#include <iostream>
using namespace std;
int main() {
int organisms = 0, growthRate, rate, days, amount = 0;
//int x; //for loop
[Code] .....
how we will increase the size of an arry during program execution. eg if the size of an array is 40 and during prog exexution we want to increase the size of an arry ,what is the procedure.
View 1 Replies View RelatedI am new to C. I've been trying to use C to code some statistical functions originally coded in R. I've encountered an interesting phenomenon. In the function foo1, I declared the array v1v2b using an actual value 1999000. The function runs fine when I call it in R.
Code:
void foo1(double *x, double *y, int *nsamp){
int i, j, k, oper=2, l;
double* v1v2=malloc(sizeof(double)*((*nsamp)*(*nsamp-1)/2 + 1));
outer_pos(x, y, nsamp, &v1v2[0]);
double v1v2b[1999000]; //<-------HERE
for(i=1; i<= 1999000]; i++){
v1v2b[i-1]=1;
} }
However, in foo2, I first create an integer variable called index, and store the value 1999000 in it. I then use it to initialize the same array. When I tried calling this function in R, it either led to a stack overflow error, or completely crashed R.
Code:
void foo2(double *x, double *y, int *nsamp){
int i, j, k, oper=2, l;
double* v1v2=malloc(sizeof(double)*((*nsamp)*(*nsamp-1)/2 + 1));
[Code] .....
I'm writing a program that writes to a report in a text file. It uses a struct but with no array. How can I write this so that the report comes out as it should because as of now after i removed the brackets from record which is the variable of the struct my report isn't printing right.
View 8 Replies View RelatedWorking on an assignment and I've hit TWO stumbling blocks. I now have to take the first line from a .txt file and use that number to determine the size of rows to create in my program. I am using fscanf but the program hangs. How can I read in this number, store it and use it in a for loop?
The second issue is after reading this number I have to print each number in the .txt file under a different column. (Note that it skips a line after reading the row count.) The .txt file is set up as follows:
9 1 3 6 4 7 8 8 6 1
The output should look sort of like:
Number 1 3 6 4 7 8 8 6 1
Here's my attempt:
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <math.h>
typedef struct{
int number;
[Code] .......
I know that if the structure doesn't fit into the stack, it needs to be put onto the heap. But what is maximum size of a win32 stack in usual case?
View 4 Replies View RelatedChange the frame window size according to font size increases.
View 3 Replies View RelatedI have a program which call only one time malloc at the start of the program. When running, I see with 'process-explorer.exe' that memory is growing in little steps. Is this normal? why?
Using Windows 7
I must take an old MFC project in VC++ 6.0 and make changes.
The problem is text size in screen is different from size in print preview.
for example with this font
Code:
CFont f50;
f50.CreateFont(100,0,0,0,FW_BOLD,0,0,0,DEFAULT_CHARSET,OUT_DEFAULT_PRECIS,
CLIP_DEFAULT_PRECIS,DEFAULT_QUALITY,FF_DONTCARE,"Frutiger LT Std 45 Light");
And this text
Code:
s=_T("Let's try to calculate the size of this text");
and with MM_LOMETRIC map mode
GetTextExtent() returns me:
On screen: (1595,99)
Ink printer + print preview: (1589,100)
PDFCreator + print preview: (1580,100)
comparing with screen size the height is bigger but lenght is smaller. I don't understand.
I can understand that different printers process the fonts in different way and then to have different lenghts. That's not the problem. The problem is I need to simulate in screen the same behaviour i will have on printer because these texts are being aligned in the document, and I don't want to see that the text si aligned different in text than in paper.
What can I do to render the text on screen with the same size I will have on the printer? Print preview is doing it. Should I change the font parameters? is something related with pixels per inch?
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].....
"
#include <stdio.h>
struct datastructure {
char character;
};
void function(struct datastructure** ptr);
[Code] ....
These codes give these errors:
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
These errors are related to
"
*ptr->character='a';
printf("Ptr: %c",*ptr->character);
"
I want to access "character" data inside the structure "trial" by a pointer to pointer "ptr" inside function "function",but I couldn't find a way to do this.
I just read and have known for a while that classes are private (members and inheritance) by default and structs are public. But my question then comes what if.. a struct inheriting from a class or a class inheriting from a struct?
View 3 Replies View RelatedSo why does this not work? As an example:
struct example {
int x; int y;
};
int main() {
example variable;
variable.x = 1;
variable.y = 2;
map<example, int> something;
something[variable] = 3;
return 0;
}
And I get a very long error message from the compiler. I tried using an enum as the key as well and that worked just fine, but I guess that's just the same as having an integer as the key. But anyway, what's the problem with this? Is there any way to make it work?
how can I call and print the Pointer:
ptr->address
Code: #include<stdio.h>
struct account {
int address;
int value;
[code]....
So i create a simple structure,that has a firstname, lastname, age, dateofbirth.I would like it if i type what I am searching for print out there is one or not.But i have some trouble with equals(in array).. i type in the same "keresettnev" as "tanulok[i].Firstname" but it thinks not the same. (it works with age..)
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct student {
char *Firstname[40];
char *Lastname[40];
int age;
[Code] ....
I am using Beej's Guide to Network Programming Using Internet Sockets. I'm just curious why I need to zero out the rest of the struct?
Code:
int main(){
int sockfd;
struct sockaddr_in my_addr;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
[Code].....
Code:
#include <stdio.h>
struct database {
int id_number;
int age;
float salary;
[Code] ....
When I compile, I get an error:
test.c|18|error: incompatible type for argument 1 of 'printf'|
note: expected 'const char *' but argument is of type 'float'|
I thought employee.salary is a float but the compiler expected 'const char'. How do I make this work?
I am working on a program which uses external hardware to acquire data. we have the option to use hardware from two different companies, each with it's own driver. However both do the same job. My program is meant to read data packets which are structured as:
typedef struct _data {
DWORD ID;
BYTE bf;
BYTE bd;
BYTE bData[8];
DWORD bt;
} data;
Now both the companis use the same data structure, but the first has defined the structure, let's say, as:
typedef struct _dataX {
DWORD ID_X;
BYTE bf_X;
BYTE bd_X_;
BYTE bData_X[8];
DWORD bt_X;
} dataX;
[code].....
I am programming my software so as t allow the customer to use the hardware of their choice. Simply select the card they are using and our program should be able to take care of the rest of stuff. I am using #ifdef directives to include the header for the corresponding hardware dll. Now I want to define my own data struct of the type:
typedef struct _dataMY
{
DWORD ID_MY;
BYTE bf_MY;
BYTE bd_MY_;
BYTE bData_MY[8];
DWORD bt_MY;
}
[code]....
and when I use _dataMY.ID_MY .. it should directly be able to see if it is _dataX.ID_X or _dataY.ID_Y, based upon the directive I have used earlier.
I've been working on a path-tracer for some time, and all along I've used structs instead of classes for vectors and matrices. Today I changed all of them to classes instead, changing none of the actual function bodies themselves, and the results were miserable to say the least.
Here's a render form before the change: [URL] ....
And here's the same render after: [URL] ....
Why this is happening, considering that none of the actual function-bodies have been changed, except for what little is needed to make the change from class to struct.
