Matrix memory allocation via a function

I am using these lines to create variable size matrices: Temp_Mat_0 = (double **)malloc((M)*sizeof(double )); for (i=0;i<M;i++) Temp_Mat_0[i] = (double *)malloc((N)*sizeof(double )); They are working fine but I keep using them repeatedly in my code.

How to use malloc to return the C string of the function

I am trying to return a C string from a function. The function is suppose to concatinate the 3 integers with commas and return the result as a char array however I'm getting garbage values. I'm assuming I'm not calling malloc correctly. Can someone a

Create an array dynamically in C ++

I have to create a matrix with the width and height determined by two parameters obtained from the writing of a file. But, in some cases when the matrix is too big, I've got a segmentation fault. I think is probably because I'm creating the matrix in

fscanf () and realloc () - read the file in the matrix

I have a problem with reading file dynamically to 2D array. I've been reading about it for a long time but I still don't know how to force my code to work. My code: http://codepaste.net/3hcbtn #include <stdio.h> #include <stdlib.h> int main(){

Is array an argument in c really the type of reference?

#include <stdio.h> #include <stdlib.h> void fun(int *arr) { arr=(int *)malloc(2*sizeof(int)); arr[0]=5; arr[1]=4; printf("in fun {%d, %d}",arr[0],arr[1]); } void anotherFunction(int *arr) { arr[0]=4; arr[1]=5; printf("in fun {%d

segmentation error using malloc

I'm new to C, so this may be a silly question to ask: What I want to do here is to input the data to the array of pointers to a structure and then print it out. But I get a segmentation fault when running into the insert function. Below is my code co

Creation of unwanted allowances / failure to release benefits

I am having a problem releasing my allocations. My allocations tool in my instruments indicates that "bitmapData = malloc( bitmapByteCount );" is the source of the allocation and that it is not being released. I am new to cocoa and xcode. How wo

Implementation of the storage in separate memory (malloc) in C

I'm trying to implement my own malloc using a segregated free list (using this textbook as a reference: http://csapp.cs.cmu.edu/), but I'm not sure how to start. I have a method, malloc_init() that uses sbrk to return a slab of memory. Within the con

Allocate a matrix in C using malloc

I wrote a C code that usea a matrix of double: double y[LENGTH][4]; whith LENGTH=200000 I have no problem. I have to increase the numbers of rows to LENGTH=1000000 but when I enter this value and execute the program it returns me segmentation fault.

Malloc behaves strangely when allocating space for ints

Probably I just lack understanding of how malloc works, but I don't see an error with my code: int amount_integers = 2; int *pointer_to_allocated_memory = (int*)malloc(amount_integers * sizeof(int)); for (int i = 0; i < amount_integers; i++) { int *a

malloc with user input

I'm trying to make a program where a user inputs a string then if they want to enter a letter they want to replace and what with. I want to use malloc to set the array but how would I do it with scanf? Please can someone help. Thanks! This is what th

Why does my empty pointer change values ​​in my program?

I have a the following in a header file. struct SortedList { void * data; struct SortedList * next; struct SortedList * previous; int (*compareFunc)(void *, void *); void (*destructor)(void *); }; typedef struct SortedList* SortedListPtr; SortedListP

Using a digital object in malloc

I am new to programming and I am trying to understand the difference between A = (char * ) malloc(sizeof(char)*n); and A = (char * ) malloc(sizeof(char)); or A = new char [n]; and A = new char; What is the default memory that a compiler is allocating

Assigning values ​​to a 2D array created using malloc

I created a 2D character array using malloc and have been trying to assign its values to '\0'. char **predicate_array = malloc(no_of_lines_in_data_map); for(int i = 0; i < no_of_lines_in_data_map; i++){ predicate_array[i] = malloc(1024 * sizeof(char)

Difference between two malloc definitions of a structure

I would like to know if there's a real difference between this: c = (struct_t *) malloc(sizeof(struct_t)); and this c = malloc(sizeof(struct_t *)); Besides avoid the cast, is the compiler takes any advantage in the second form respect the first? Or t

C matrix, allocation does not zero all the elements?

I'm trying to write a little matrix program. Using doublke pointers doesnt work so I figure the easiest way is to have a struct that has the #rows and #columns and a 1d array as the matrix. But there is some error in the initiation of the matrix as i

Use of cudamalloc (). Why the double pointer?

I am currently going through the tutorial examples on http://code.google.com/p/stanford-cs193g-sp2010/ to learn CUDA. The code which demostrates __global__ functions is given below. It simply creates two arrays, one on the CPU and one on the GPU, pop

c ++: local array definition against a malloc call

What is the difference between this: somefunction() { ... char *output; output = (char *) malloc((len * 2) + 1); ... } and this: somefunction() { ... char output[(len * 2) + 1]; ... } When is one more appropriate than the other? thanks all for your a

Corruption issues

Inside my template function I have the following code: TypeName myFunction() { TypeName result; void * storage = malloc( sizeof( TypeName ) ); /*Magic code that stores a value in the space pointed to by storage*/ result = *(TypeName *)storage; free(

allocate the matrix in C

i want to allocate a matrix. is this the only option: int** mat = (int**)malloc(rows * sizeof(int*)) for (int index=0;index<row;++index) { mat[index] = (int*)malloc(col * sizeof(int)); } Well, you didn't give us a complete implementation. I assume th

Potential problem with standard malloc'ing characters C

When answering a comment to another answer of mine here, I found what I think may be a hole in the C standard (c1x, I haven't checked the earlier ones and yes, I know it's incredibly unlikely that I alone among all the planet's inhabitants have found