dynamic-memory-allocation

I know I can do new char[n] to create an array of n chars. This works even when n is not a compile time constant. But lets say I wanted a size variable followed by n chars: My first attempt at this is the following: struct Test { std::size_t size; char a[]; }; However it seems new Test[n] doesn't do what I expect, and instead allocates n size s. I've also found that sizeof(std::string) is 4 at ideone, so it seems it can allocate both the size and the char array in one block. Is there a way I can achieve what I described (presumably what std::string already does)? While you can do this (and it

programming language: C platform: ARM Compiler: ADS 1.2 I need to keep track of simple melloc/free calls in my project. I just need to get very basic idea of how much heap memory is required when the program has allocated all its resources. Therefore, I have provided a wrapper for the malloc/free calls. In these wrappers I need to increment a current memory count when malloc is called and decrement it when free is called. The malloc case is straight forward as I have the size to allocate from the caller. I am wondering how to deal with the free case as I need to store the pointer/size mapping

I know about algorithms to allocate/deallocate a 2D array dynamically, however I'm not too sure about the same for 3D arrays. Using this knowledge and a bit of symmetry, I came up with the following code. (I had a hard time visualizing in 3D during coding). Please comment on the correctness and suggest any better alternative (efficiency-wise or intuitively), if any. Also, I think both these 2D and 3D arrays can be accessed normally like static arrays like arr2D[2][3] and arr3D[2][3][2]. Right? Code for 2D //allocate a 2D array int** allocate2D(int rows,int cols) { int **arr2D; int i; arr2D =

From man realloc:The realloc() function returns a pointer to the newly allocated memory, which is suitably aligned for any kind of variable and may be different from ptr, or NULL if the request fails. So in this code snippet: ptr = (int *) malloc(sizeof(int)); ptr1 = (int *) realloc(ptr, count * sizeof(int)); if(ptr1 == NULL){ //reallocated pointer ptr1 printf("Exiting!!\n"); free(ptr); exit(0); }else{ free(ptr); //to deallocate the previous memory block pointed by ptr so as not to leave orphaned blocks of memory when ptr=ptr1 executes and ptr moves on to another block ptr = ptr1; /

How am I supposed to use dynamic memory allocations for arrays? For example here is the following array in which i read individual words from a .txt file and save them word by word in the array: Code: char words[1000][15]; Here 1000 defines the number of words the array can save and each word may comprise of not more than 15 characters. Now I want that that program should dynamically allocate the memory for the number of words it counts. For example, a .txt file may contain words greater that 1000. Now I want that the program should count the number of words and allocate the memory accordingly

I don't truly understand some basic things in C like dynamically allocating array of arrays. I know you can do: int **m; in order to declare a 2 dimensional array (which subsequently would be allocated using some *alloc function). Also it can be "easily" accessed by doing *(*(m + line) + column) . But how should I assign a value to an element from that array? Using gcc the following statement m[line][column] = 12; fails with a segmentation fault. Any article/docs will be appreciated. :-) The m[line][column] = 12 syntax is ok (provided line and column are in range). However, you didn't write