Hello, I am using a struct and I want to initialize a maximum of 10 ports. However, when the program is running it could be a lot less, we don't know until run-time. However, this will be the max. I have never done struct like this before, as I normally dynamically allocate using calloc and delcare like this *ports as the value type. ...
Hello, C99 gcc I keep getting this error. I have a struct outside main. And inside main I am trying to allocate on the stack using calloc. I can't seem to find out what is wrong. Thanks for any advice, error: expected expression before ‘)’ token /* global */ struct port_data_t ...
What is the difference between doing: ptr = (char **) malloc (MAXELEMS * sizeof(char *)); // OR ptr = (char **) calloc (MAXELEMS, sizeof(char*)); ??? EDT: When is it a good idea to use calloc over malloc or vice versa? ...
Hi again! I am still learning C and I'm having some trouble figuring out how to handle this. Well, I have two structs: struct myStruct { ... struct myString *text[5]; ... } allStructs; struct myString { char part[100]; }; The objective is to have allStruct[n] point to 5 different parts of a text divided into lines of...
Hello, When I alloc memory outside a while loop for example, is it okay to free it inside it ? Are these two codes equivalent ? int* memory = NULL; memory = malloc(sizeof(int)); if (memory != NULL) { memory=10; free(memory); } int* memory = NULL; memory = malloc(sizeof(int)); if (memory != NULL) { memory=10; } free(memory); ...
I have a command line C program for which I use the calloc() function to assign some memory for a struct which also has a struct in it with some memory assigned. If I use the free() function to release the memory from the parent struct, will it also release the memory from the child struct? Or should I release the memory from the child...
I'm trying to allocate a block of memory and then copy data into that space. I made this simple program and it doesn't do what I expect it to do. Could someone please point out my faulty reasoning. Thanks. #include <stdio.h> #include <stdlib.h> void main(void) { int t1 = 11; int t2 = 22; int *bufptr; bufptr = calloc(2, sizeof(int)); ...
Looking at this question that has just been asked: http://stackoverflow.com/questions/2231317/inconveniences-of-pointers-to-static-variables would doing something like this be considered bad practice, then? char* strpart(char* string, int start, int count) { char* strtemp; int i = 0; int j = 0; int strL = strlen(string); ...
Hi, What is the advantage of zeroing out memory (i.e. calloc over malloc)? Won't you change the value to something else anyways? -Chris ...
I've read with interest the post C difference between malloc and calloc. I'm using malloc in my code and would like to know what difference I'll have using calloc instead. My present (pseudo)code with malloc: Scenario 1 int main() { allocate large arrays with malloc INITIALIZE ALL ARRAY ELEMENTS TO ZERO for loop //say 100...
Hi, I'm trying to create a 2D array of chars to storage lines of chars. For Example: lines[0]="Hello"; lines[1]="Your Back"; lines[2]="Bye"; Since lines has to be dynamically cause i don't know how many lines i need at first. Here is the code i have: int i; char **lines= (char**) calloc(size, sizeof(char*)); for ( i = 0; i < size; ...
Dear Friends, I am trying to trace a segfault with valgrind. I get the following message from valgrind: ==3683== Conditional jump or move depends on uninitialised value(s) ==3683== at 0x4C277C5: sparse_mat_mat_kron (sparse.c:165) ==3683== by 0x4C2706E: rec_mating (rec.c:176) ==3683== by 0x401C1C: age_dep_iterate (age_dep.c:28...
The following code is an example from the NCURSES menu library. I'm not sure what could be wrong with the code, but valgrind reports some problems. Any ideas... ==4803== 1,049 (72 direct, 977 indirect) bytes in 1 blocks are definitely lost in loss record 25 of 36 ==4803== at 0x4C24477: calloc (vg_replace_malloc.c:418) ==4803== by ...
Possible Duplicate: c difference between malloc and calloc Please explain the significance of this statement, Another difference between the malloc() and calloc() functions is that the memory allocated by malloc( ) function contains garbage values, while memory allocated by calloc( ) function contains all zeros...
A lot of c/malloc()'s in a for/while/do can consume a lot of time so I am curious if any operating system buffers memory for fast mallocs. I have been pondering if I could speed up malloc's by writing a "greedy" wrapper for malloc. E.g. when I ask for 1MB of memory the initial allocator would allocate 10MB and on the 2nd, 3rd, 4th etc.....
Seem to have a memory allocation problem and think it's because in my struct, there is a pointer to an array of another struct. However, I'm not initializing this array and not sure how: typedef struct listitem { struct listitem *next; Entry *entry; } ListItem; typedef struct list { ListItem *table[100]; } List; List *init...
I have a struct which is a node, and another which is a list of these nodes. In the list struct, its an array of nodes, but instead of an array, it's a pointer to pointer with a size integer: typedef struct node { struct node *next; MyDef *entry; } Node; typedef struct list { Node **table; int size; } List; List *init...
A struct like the following works fine, I can use t after calling malloc(sizeof(mystruct)): struct mystruct { MyDef *t[5]; }; I want to be able to dynamically set the length of the array of MyDef, like the following: struct mystruct { MyDef **t; int size; }; What do I need to do additionally to malloc(sizeof(mystruct)) to get th...