WriteMemoryCallback

WriteMemoryCallback.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <curl/curl.h>

//struct in C is similar to class
struct MemoryStruct {
  char *memory;
  size_t size;  //size_t is an unsigned integer type of at least 16 bit
};

/*Callback means any executable code taht is passed as an argument, which is expected 
  to execute the argument at a given time */
static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
  size_t realsize = size * nmemb;
  struct MemoryStruct *mem = (struct MemoryStruct *)userp;
 
 //realloc(pointer to data, new size)
 //mem->memory means getting the member called `memory` from struct `mem` points to
  char *ptr = realloc(mem->memory, mem->size + realsize + 1);
  if(ptr == NULL) {
    /* out of memory! */ 
    printf("not enough memory (realloc returned NULL)\n");
    return 0;
  }
 
  mem->memory = ptr;
  //memcpy(destination, source, number of bytes)
  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;
 
  return realsize;
}