free

Pointers are a really tricky thing in C. For a lot of people is hard to understand it, so for a good understanding I wrote following code: #include <stdlib.h> #include <stdio.h> int main(int argc, char *argv[]) { int *p; // pointer -> will be dynamic allocated int *a; // array -> will be dynamic allocated // print before allocate memory (1) printf("&p: %p\tp: %p\t*p: %d\n", &p, p, *p); printf("&a: %p\ta: %p\t*a: %d\n", &a, a, *a); printf("\n"); // allocate memory (2) p = (int *)malloc(sizeof(int)); a = (int *)malloc(sizeof(int) * 10); // print after allocate, but before give a value to

I am trying to return an array using malloc in a function: char* queueBulkDequeue(queueADT queue, unsigned int size) { unsigned int i; char* pElements=(char*)malloc(size * sizeof(char)); for (i=0; i<size; i++) { *(pElements+i) = queueDequeue(queue); } return pElements; } The problem is that I need to free it because my MCU's heap size is limited. But I want to return it so I cannot free it in the function, right?. Can I free the allocated memory outside the function (where I call the function). Is there any best practices for this? Thank you in advance! As the memory allocated by malloc() is

I have a C function that mallocs() and populates a 2D array of floats. It "returns" that address and the size of the array. The signature is int get_array_c(float** addr, int* nrows, int* ncols); I want to call it from Python, so I use ctypes. import ctypes mylib = ctypes.cdll.LoadLibrary('mylib.so') get_array_c = mylib.get_array_c I never figured out how to specify argument types with ctypes. I tend to just write a python wrapper for each C function I'm using, and make sure I get the types right in the wrapper. The array of floats is a matrix in column-major order, and I'd like to get it as a

Today, I appeared for an interview and the interviewer asked me this, Tell me the steps how will you design your own free( ) function for deallocate the allocated memory. How can it be more efficient than C's default free() function ? What can you conclude ? I was confused, couldn't think of the way to design. What do you think guys ? EDIT : Since we need to know about how malloc() works, can you tell me the steps to write our own malloc() function That's actually a pretty vague question, and that's probably why you got confused. Does he mean, given an existing malloc implementation, how would

Could somebody tell me the difference between: int *p; p=(int*)malloc(10*sizeof(int)); free(p); or int *p; p=(int*)malloc(10*sizeof(int)); p=NULL; free will deallocate the memory that p points to - simply assigning it to NULL will not (and thus you will have a memory leak). It is worth mentioning that it is good practice to assign your pointer to NULL AFTER the call to free , as this will prevent you from accidentally trying to access the freed memory (which is still possible, but absolutely should not be done). There is no garbage collection in C, so if you don't explicitly free a chunk of