I'm trying to make an application and I need the length of the array of a struct. Like this:
struct myStruct {
int integer;
};
myStruct struct[] =
{
1,
2,
};
I want to get how many ints are in the array...
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'm working with arrays that might have NULL bytes in them and I'm wondering how to determine the length of the array or store it somewhere with the array (strlen() won't work because of the NULL, right?).
I've found advice like store the length of the array in the first byte of the array, but since sizeof(size_t) is 8 should I leave the first 8 bytes for the length?
Would it be better do define my own structure which would store the array and its length? What's the usual way these things are handled in practice?
I was reading in a book I had about C that an array has at the very end a "null character" signifying the end of the string inside it, "/o". So that made me think, "I guess one needs to declare arrays as having 1 extra space than one expects the array to need. I wonder what will happen if I exceed the array length?" So I made a program to test it out. Here is the program/results:
Code:
#include <stdio.h>
int main(void){
char name[3];
printf("
What's your name?
");
scanf("%s", name);
}
[code]....
As you can see my name was able to fit in the array somehow even though I only allocated 3 bytes to the array. I tried again using my legal first name, Benjamin, and it was still able to fit. How is the array able to hold my name when I declared it as only having 3 bytes?
i having a code to pass in array as argument, but the length returned is 1. This is not match with the array size.
int Getsize(int Array[])
{
int len = sizeof(Array)/sizeof(int);
cout << len << "
";
}
int main()
{
int X[] = {45, 12, 54, 83, 41, 36};
getsize(X);
}
I can't find any method of retrieving the length of an array except for doing this:
string first[] = {"a","be","see"};
int length = sizeof(first)/sizeof(first[0])
This is a very unconventional way of getting the length of an array.
first->length() would return 1 because it returns the number of letters in the first element of the array (which actually makes no logical sense).
first.size() would return 1 aswell as it's practically the same thing.
Since getting the length of an array is such a fundamental feat, how come I can't find a decent method of doing it?
Is there no buildt in method for this? If there is not, why has it not been implemented in the std?
I have a program with the following code, and I need to be able to either change the value of any or all of the strlen or to replace one or all with a temp array value. All values of the expression are arrays.
if (::strlen(tc_buf) + ::strlen(maxtime_buf) + ::strlen(" ") < sizeof(localBuf))
I am working on a c-programm. In this program I have to convert the amount of money I read on two variables into the corret format. I got Euros and cents on 2 ints. But now I want to add both of those variables in a String (char array). Also i want to find out the length of the new char array.
View 2 Replies View RelatedHow can I obtain the length of an array that has been sent throughout a function. In the following code, I obtain "2" as output, while I was expecting "5".
void call(int a[]) {
cout<<sizeof(a)/sizeof(int);
}
int main() {
int* a=new int[5];
call(a);
}
How can I properly call this function so I can obtain the correct array size?
How can i change or add a cell to an array without knowing its length ? (I mean that I shouldn't know the length I need to make the length dynamic so i can add a cell)we just learned Dynamic assignment(I hope this is the correct name) and Pointers.
View 5 Replies View RelatedThis code snippet compiles and runs fine
Code:
#include <stdio.h>
int main(void) {
int i, a[i];
i=2;
for(int n=0; n<=i; n++)
a[n]=0;
[Code] .....
It prints out 3 "0", but when slightly changed
Code:
#include <stdio.h>
int main(void) {
int i, a[i];
i=200;
for(int n=0; n<=i; n++)
[Code] ....
It compiles fine but core dumps when run, how come? i'm using gcc version 4.4.7, and compiling like this
gcc -std=c99 test.c -o test
I believe that everything is fine except that I can think of the condition can be inserted inside the parentheses ..
#include <iostream>
using namespace std;
int main() {
int i=0, k=0;
char *string_n, **matrix, temp;
[code].....
How to write a function that receives an integer array along with its length. the function calculates and returns the sum of the squares of all the odd numbers in the array?
View 2 Replies View Relatedi have to read a file with between 5 and 10 pairs of numbers, each on a different line. i can read the file, and wrote something to save the length of the file as a variable, but when i use it i start returning crazy data. the problem is in the do while loop and i want to change the i< in the for loop to "lines" so the code stops when the last digit is read. if i use i<10 the file has extra digits is the file is only 8 or 5 pairs of numbers.
FILE *Fpointout;
FILE *Fpointin = fopen ("test.txt","r"); //read this one
Fpointout = fopen ("out.txt","w"); //write this one
if (Fpointin == NULL) //if no file in source {
printf ("File does not exist."); //tell user it is not there
[Code] .....
I want to ask for a number as an input during runtime and then create an 2-dimensional array of size as specified by user. i.e. if the user inputs 3, the array should be of size 3X3, and likewise...
View 9 Replies View RelatedI wrote this simplified version of a program i am writing that parses data in UDP packets. In the process of doing so i pretty much answered all my questions and fix all the problems i was having.
decodeSystemMap function will be in loop, and will proccess packets that have mostly the same data, only a few items will be added or changed or deleted.
whats the best way to check if there are any new, deleted, or removed items in the packet and only modify those?
Is there anything unsafe / dangrous about the way the code is now?
Code:
/* * File: main.c
* Author: david
*
* Created on May 23, 2013, 11:57 AM
*/
#include <stdio.h>
#include <stdlib.h>
[Code] ....
I am working on an assignment identical to another post from a couple years ago, for reference here is the thread:
array of pointers to structures sorting addresses by zip code
They way it is written on that thread is almost identical to the way the teacher implied to have it done (only wrote part of the input block). But I am having an error:
When it gets to the output section it outputs then next name along with the zip code... I tried strncpy and strxfrm but both cause more problems than they did work.
The last part of the project is to have the output put out in order of least zip code to most zip code (00000<99999), so this is causing me a real problem and I do not see what exactly is making this happen.
Here is my code (we dont HAVE to use gets but professor suggested using it for this assignment, next lab is to rewrite this using files and fgets rather than I/O redirection):
header.h Code: #ifndef lab_6b_7b_Header_h
#define lab_6b_7b_Header_h
//header file intiating other headers
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct{
[code]....
I have not started the sorting code because I cannot get past this, but once I have proper zip codes I am sure I can make a sort function no problem.
I am using xcode with some breaks to read variables as various points and do not notice anything wrong until it makes it to the output functions, although this page briefly pops up between input and output functions when the breaks are up:
I am trying to pass a struct through an array to another array from one microprocessor to another microprocessor and then dereference that array to update the same exact struct on the other microprocessor.My goal is to always have values inside of both structs while sending any updates to the struct on the other microprocessor in the mean time but I seem to be looping through the data and the members of the struct seem to be cleared out after every clock cycle. I can verify this by the flashing of my leds which the struct controls.
FIRST MICROPROCESSOR
Code:
extern struct i2c_data * TX_Data;
extern struct i2c_data TX_Data_1;
extern struct i2c_data TX_Data_2;
}
[code]....
In a book I'm reading, the author has the following struct:
struct VertexPos {
XMFLOAT3 pos;
};
Where XMFLOAT3 is a structure with x,y,z floating point values within. He declares and initializes an array as the following.
VertexPos vertices[] =
{
XMFLOAT3(0.5f, 0.5f, 0.5f),
XMFLOAT3(3.3f, 5.6f, 3.6f),
XMFLOAT3(-4.5f, 2.2f, 6.4f)
};
It doesn't make sense to me why this is working. The way my mind is thinking about this is that vertices is an array of type VertexPos, so then why can it be initialized with objects of type XMFLOAT3?
Code:
#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;
struct inventory
[Code]...
This is my program output Enter the file name : "filename".txt ..... (Nothing shows up)
What I'm trying to do with this code is an address book and I have an array of pointers which are returned by malloc whenever I need to add an extra entry in the address book. What I need to do is search for a specific entry using bsearch. I've got an inqSort() function that sorts the table and runs normally, but my program crashes when I try to use bsearch.
Code:
typedef struct {
char name[20];
char phone[14];
} abEntry;
[Code] ....
Every time an entry is inserted, I inqsort() the array so it's always sorted, and it works as expected. But when I try to call findEntryUI(); from the main() function, the program crashes after entering the name I want to search.
Do you have to allocate memory(malloc) for an array of structs? Example:
Code:
typedef struct{
char * name;
}First;
struct name{
First fname;
};
struct name Names[10];
I have to search an array of struct students on the basis of their first names, last names and roll numbers .. so far i am done with the input of the student first , last names and roll numbers . I have problem in searching the array ..
Code:
#include <iostream> Code: #include <string>
using namespace std;
struct Student {
string FirstName ;
string LastName ;
[Code] ....
I basically just want a function that tells me if 'X' or 'O' won in a tic-tac-toe game. I don't care about the visuals, I just want a function that tells me if 'X' or 'O' won. If X wins, return 0. If Y wins, return 1.
How to do the diagonals, but as far as the across and down wins, I know I have to use a nested for loop, but am a little stuck, as to exactly how to set it up.
#include <iostream>
using namespace std;
struct TTT{
char array[3][3];
unsigned moves;
[Code] ....
Here's the definition of my struct:
struct Speaker {
static int numElem;
string name;
int number; // Phone
string topic;
float fee;
};
// IN main() FUNCTION
Speaker s[10];
The goal is for numElem to keep track of how many of the 10 elements are in use. However, I'm not sure the proper way to access the element, if it's even possible.
#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;
struct inventory {
int barcode;
char description[512];
[Code] ....
This is my text file
20123451
Sugar packet (1 kg)
2.50
560
21347652
Milo 3-in-1
12.50
200
20123453
Salt (1kg)
4.50
270
21347654
Nescafe 3-in-1
12.50
400
20123455
Tamatoes
4.00
100
21347656
Cucumbers
4.00
280
This is my program output
Enter the file name : "filename".txt
..... (Nothing shows up)