malloc 28 29 in c and c 2b 2b

1/* malloc example: random string generator*/
2#include <stdio.h>      /* printf, scanf, NULL */
3#include <stdlib.h>     /* malloc, free, rand */
4
5int main ()
6{
7  int i,n;
8  char * buffer;
9
10  printf ("How long do you want the string? ");
11  scanf ("%d", &i);
12
13  buffer = (char*) malloc (i+1);
14  if (buffer==NULL) exit (1);
15
16  for (n=0; n<i; n++)
17    buffer[n]=rand()%26+'a';
18  buffer[i]='\0';
19
20  printf ("Random string: %s\n",buffer);
21  free (buffer);
22
23  return 0;
24}