Someone

#include <stdlib.h>
#include <time.h>
#include <stdio.h>

int RandomString(char **str, int len)
{
  int rc = 0; /* 1 indicates success */
  size_t len_ = len;
  if(str != NULL)
  {
    *str = malloc(len_ + 1);
    if(*str != NULL)
    {
      const char sym[] =
        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "\"%^&*()_-abcdefghijklmnopqrstuvwxyz"
        "+=[]{}\\|,<.>/?"; /* did I miss any? */
      size_t maxsym = sizeof sym / sizeof sym[0] - 1;
      size_t i = 0;
      while(i < len_)
      {
        int r = maxsym * (rand() / (RAND_MAX + 1.0));
        (*str)[i++] = sym[r];
      }
      (*str)[i] = '\0';
      rc = 1;
    }
  }
  return rc;

}

int main(void)
{
  int rc = 0;
  int maxtrials = 20;
  char *s = NULL;
  srand((unsigned)time(0));
  while(rc == 0 && maxtrials-- > 0)
  {
    if(RandomString(&s, 42))
    {
      printf("%s\n", s);
      free(s);
    }
  }
  return 0;

}