generating random printable ascii characters in c

i'm trying to write a program for testing purposes that generates a sequence of pseudo-random printable ASCII characters, where you put in the command line how many characters you want. right now it's not working so well; the sequence is almost always majority ?s, and it doesn't开发者_如何学编程 always print the number of characters i tell it to print. here's my code; what's wrong with it? i use the time as a seed for the random function.

note: it's not worth it to me to use any algorithm more complicated than one using srand() and rand().

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

int main(int argc, char *argv[]) {
   int c;
   int i;
   int limit;

   sscanf(argv[1], "%d", &limit);
   srand((unsigned int)time(NULL));

   for (i = 0; i < limit; i++) {
      c = rand();
      if (c != 9 && c != 10 && c <= 32 && c >= 127) {
         i--;
      }
      else {
         putchar(c);
      }
   }
   return 0;
}

thanks!

Try fixing this line:

  if (c != 9 && c != 10 && c <= 32 && c >= 127) {

should be:

  if (c != 9 && c != 10 && (c < 32 || c >= 127)) {

But this would probably be better:

  if (!isprint(c)) {