And now I want to allocate memory, for a variable number (so an array) of example_struct, so I first do:
Code:
example struct *all_struct;
int total_num = 3;
//will be set somehow, but for the example I set it on 3 all_struct = malloc (sizeof(example_struct) * total_num);
And now, as far as I now, I will have to allocate for each field of the structure memory, in order to be able to use it later. But I have problem at this point, a problem of understanding:
- I just allocated memory for 3 structures, but don't I have to allocate then memory for each structure separately, or can I just now allocate the fields like this:
I'm making some multi-threaded program, but thats not my problem as i've done that already. I have a class with user-functions containing a structure which then contains a two dimensional array for each user with 25 elements. So I dont want to limit the user and make the array for example with just 10 rows, but allocate the needed memory to match the amount of 'users' a potential user of my program would want. The problem is, that i know how i should allocate it using 'new int' but it just doesnt work ! It gives an error:
Then, in some completely other class function inside the file mentioned above: (I know i could do a function in CUsers class which could allocate the memory, but I have this function which is used for some other things and it already has the amount of max users
void OtherClass::somefunction(maxusers) { // This gives an error: Error: no operator "=" matches these operands curUsers->uData.userNumbers = new int*[maxusers]; //maxusers is the int variable of max users specified by the client // However this doesn't for( int i = 0 ; i < maxusers ; i++ ) curUsers->uData.userNumbers[i] = new int[25]; // 25 columns, this doesnt give any error }
I'm not really sure what I'm doing wrong. Doing this in some function from CUsers class works (without curUsers-> or with, doesn't give any error) but doing it from some other class's function doesnt.
I want to be able to dynamically allocate and index an array like the following: vv2d[1][2].x and vv2d[1][2].y. In order to accomplish that I have chosen to use a std::vector of a std::vector of a 2D point class.
Code: /// Here is my templated version of a 2d point class which I have adopted from /// one by Alexander Chernosvitov, Function Graphics, 2001 (see ogview.h) /// http://www.codeguru.com/cpp/g-m/opengl/article.php/c5581/Function-graphics-in-3D.htm template <typename T>
[Code]....
Boundary violation occurs as soon as vv2d[1][0].x is encountered. I believe the problem is my inability to dynamically allocate the size of the (primary) typedef vector. However, eliminating the typedef for the following does not change the result. Further examination shows the vv2d[1][0] size and capacity to be 0.
I am having issues freeing memory that I allocated when adding a node to a doubly linked list. I have tried adding free() at the end of the remove function from the list with no luck. I have tried using all sorts of temporary nodes and dummy nodes to free without losing node information. Have tried storing current node, moving to next one, then freeing the old current one, without luck. Everytime I try to free a node it destroys the list. It loses important node information and can no longer operate properly and I am met with all sorts of memory crashes. I will post my add and delete nodes functions here:
/** * Adds a node to a given list * * @param q pointer a a list * @param node pointer to the node to be added */ void list_add(list *q, path *node){ path *pn; if(!(pn = (path*)malloc(sizeof(*pn)))){ perror("malloc"); exit(1);
[Code] ....
Those free's at the end are to get rid of nodes I malloced in find_path. This find_path works really well when run once lol. It finds shortest path and prints it no problem, but doing it over and over again will be problematic as it is leaking almost every bit of memory it uses />.
So in short, how to free an allocated node when I remove it from a list while still being able to use it? I have tried moving the remove function to different locations like the end of the file and still no luck. I even tried allocating a new current_node each iteration of while loop, using it, then freeing it at the end of the while loop and took out the allocation in the list_add() function. This didn't work either />. How to stop the leakage.
I've been working on this program and am finished with what I want it to accomplish. But the last step I'd like to take is to delete the linked list and free all the memory. When I free the memory the way I am right now, the program breaks. I'm not sure how I should go about freeing and setting things to NULL.
I have a program that stores health information the user inputs, one person at a time. The program works perfectly with the exception of storing the data...I need to open a file and read what health data it has in it already, if any, but store the new changes, and appended data to the array of structures, to the data in memory. All of the information is only saved back in the file once the program terminates. I'm not sure how to go about doing this, so I am also not sure what to put in the function for "Save and Exit" that the user can choose in order to exit the program.
# include <stdio.h> # include <math.h> # include <stdlib.h> # include <malloc.h> }
[code]...
I am compiling it on a 64 BIT ubuntu machine having 64GB ram using gcc 4.6 compiler. I am getting the following output Error allocating memory. But (914*866*2724) is approximately 8 GB, Whats wrong with the code?
I wrote the following C++ constructor, and I get an error - BUFFER too small on strcpy_s
Trace::Trace(const char *str) { if (str) { int len = strlen(str); this->m_name = new char[len+1]; // asking for 'len+1' memory elements of char strcpy_s(m_name, len, str); // **** I get here an error "BUFFER TOO SMALL" ****
This is what I'd expect, but I can't find any evidence online in C standards or elsewhere:
1. Works as expected, sets the value of a.num1 to 2. 2. Works as expected, sets the value of b.num1 to 2. 3. Works as expected, sets the value of a.num2 to 2. 4. Works as expected, sets the value of b.num2 to 2. 5. Works as expected, sets the value of b.num1 to 2. 6. Works as expected, sets the value of a.num1 to 2. 7. Works as expected, sets the value of b.num1 to 2. 8. Crashes/Memory Corruption, attempted to alter memory outside struct. 9. Works as expected, * ss1 == * ss2 10. Crashes/Memory Corruption, attempted to alter memory outside struct.
I've tested simular code on my machine (Xubuntu 14.04LTS compiled with gcc on -O3) and it appears to be reliable, given that you stick with acessing the type tagged in the struct or the common initial union struct members (in this case num1).
I'm trying extremely hard to understand pointers and I have the basic concept down.. I feel as though my knowledge of dynamically allocated pointers and pointers in general is not enough to understand the logic behind what I'm trying to do. The problem is that the donations array must be able to accept any number of donations. I've made it do just that, but there is also an array of pointers which must each point to the same element in the donations array. The program works if I assign int *arrPtr[100] for example, but it does not work if I try to dynamically allocate it to accept the same number of elements for donations entered by the user. Here it's the snippet
#include <iostream> using namespace std; //Function Prototypes
Working on this one from the Jumping into c++ book. The book asks that I create a multidimensional array at run time based on user input and fill it with a multiplication table
My code compiles fine but throws an uninitiated error for p when I try and run it.
Code: void multiDimentionalMultiplication(int x, int y, int z){ int ***p; **p = new int[x]; std::cout << "Allocating array.
I am trying to figure out the syntax to dynamically allocate a single dimension of a triple dimensional array. Basically i have a 2D array of structs. but each struct is an array (basically rows of the information). The rows of this structure need to be allocated dynamically, but the height and width of the overarching structure are static.
Basically: Struct * ts_FieldInfo[100][100] = new Struct[Class.returndataitems()];
so I have this code that dynamically allocates a pointer array increasing and removing elements of the array as its operated on.then it sorts and prints out the array when the user is finished operation on the array. i get this error message when running the program though.
"Unhandled exception at 0x0F474F98 (msvcr110d.dll) in Lab10_VarArray.exe: 0xC0000005: Access violation reading location 0xCCCCCCC0."
this is my code
#include <iostream> #include <cstdlib> #include "Header.h" using std::cout; using std::endl; using std::cin; int main(void) { char op='x';
This is a homework assignment where I have to read a file into a dynamically allocated 2d array. The file format is 10 Jim 3.6 Jake 4.0 Will 3.0 Sara 3.4 Mike 2.5 Ellen 2.9 Melissa 3.9 Eric 3.8 John 3.5 Beth 3.9
where 10 is the number of students followed by the students and the gpa's. There is more to the program but I have not implemented it yet because I am getting a segmentation fault. The output I am getting when I print the array is Jim 3.6 Jake 4.0 Will 3.0 Sara 3.4 Segmentation fault
I can see where the problem lies. If I raise value for row when I am allocating the rows of the array, all of the names print. I just do not see why I need to. From my understanding the row * sizeof(char*) should give me enough room for 10 entrie.
Code: #include <stdio.h> #include <stdlib.h> void sort(); int main()
I'm trying to dynamically allocate a standard array at runtime in the function of a class where the array is "owned" by the calling class. The calling class knows nothing about the array before it makes the call to create the array other than the datatype of the array. But the full array of data needs to be returned.
It appears that the pointer being passed makes a copy of the pointer on the stack and then when the function returns it pops it off the stack and the array is a memory leak because the pointer is once again a nullptr as it was before being passed and the array has not been deallocated with delete yet (as it should not have been).
(Edit:Unexpected value of MyArray being a nullptr instead of pointing to an array after returning from line 09.)
class Class1 { void FunctionA() { Class2 OwnedClass; int* MyArray = nullptr; int SizeOfMyArray = 0;
I'm having a bit of an issue here. I have a linked list where each node contains a pointer to a string (which has been malloc'd when the node was created and inserted) and a pointer to the next node in the linked list.
I'm creating a function which will free the node (or effectively delete it). However, I'm receiving a free(): invalid pointer error.
How do I store pointers to a struct in an array ? I am using sprintf to concatenate some values together and then output it to an array in its 1st argument. A portion of my code is shown below.
I am going to be using a boolean variable to mark whether or not a specific field has had data entered into it. I figure the best way to do that is to initialize all the elements of the structures to 0. However, with strings and with the nested structure, I'm not sure how to do this.
I have to write a program that reads from a text file, which contains a list of stock hourly prices and the company names. Something like this:
78.52 82.56 75.10 71.97 Water Company 22.40 25.68 21.37 22.96 Mega Shipping Inc
There's suppose to one array of companies, where each company will be kept in a structure that contains: a pointer for the name, an array of the prices, and the average price for the day. The structures will be kept in an array of structures.
My question is, how do I read the data from the file and put the data from each line into the next structure in the array of structures? I read the numbers in fine. I just use:
