Random tokens

[Unregistered]

Hello -
I've tokenized a string of characters, but now I am trying to figure out how I can display the tokens randomly on the screen. Thanks for your help!

[Prelude]

How randomly do you need them? If it's only a matter of printing any string to the screen without worry about the same one being printed more than once then this would work fine:

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

static void printRandom ( const char *c[], int size )
{
  int i;
  for ( i = 0; i < size; i++ )
    printf ( "%s\n", c[( rand() * size ) / RAND_MAX] );
}

int main ( void )
{
  int i;
  char a[] = "Everybody loves working with C-Strings, right?",
       copy[BUFSIZ],
       *b[BUFSIZ] = {0},
       *tok;
  srand ( (unsigned)time ( NULL ) );
  strcpy ( copy, a );
  tok = strtok ( copy, " " );
  for ( i = 0; tok != NULL; i++ ) {
    b[i] = tok;
    tok = strtok ( NULL, " " );
  }
  printRandom ( b, i );
  return EXIT_SUCCESS;
}

-Prelude

[master5001]

I don't like to use strtok because it requires a lot more care to keep error free. So here is my alternative:

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

//i hate strtok....
char **makemultistr(char *str, int *size) {
    int i, n;
    char *ptr1, *ptr2, **rtrn_str;

    for(ptr1 = strstr(str, " "), i = 0; ptr1 != NULL; i++, ptr1 = strstr(ptr1, " ")) {
        if(ptr1 != NULL)
            ptr1++;
        //i will hold the number of tokens after the for loop is done
    }

    *size = i;
    rtrn_str = (char **)malloc(i*sizeof(char *));

    if(rtrn_str != NULL) {
        for(ptr1 = strstr(str, " "), i = 0; ptr1 != NULL; i++, ptr1 = strstr(ptr1, " ")) {
            if(ptr1 != NULL)
                ptr1++;

            ptr2 = strstr(ptr1, " ");
            n = (ptr2 != NULL)?ptr2-ptr1:strlen(ptr1);
            rtrn_str[i] = (char *)malloc(n);
            if(rtrn_str[i] != NULL)
                strncpy(rtrn_str[i], ptr1, n);
            else
                fprintf(stderr, "malloc() error.\r\n");
        }
    } else
        fprintf(stderr, "malloc() error.\r\n");

    return rtrn_str;
}

void freemultistr(char **str, int size) {
    int i;
    for(i = 0; i < size; i++)
        free(str[i];

    free(str);
}

int main(void) {
    char str[] = "This is much easier to do now...",
        **str2d;
    int size, i;

    str2d = makemultistr(str, &size);
    srand(time(NULL));   //set random seed

    if(str2d == NULL)
        return 1;

    while(1)    //infinite loop
        printf("%s\r\n", str2d[(long)(rand()%time(NULL))%size]);

   //if this loop weren't infinite it would be a good idea to do this
   freemultistr(str2d);  

    return 0;
}

[Prelude]

>I don't like to use strtok because it requires a lot more care to keep error free.
To each their own, though you'll rarely have problems with strtok if you take the proper care in using it.

-Prelude

[master5001]

>>To each their own, though you'll rarely have problems with strtok if you take the proper care in using it.

The other reason I don't like using it is because you have two options with strtok. Make a copy of the string that will be tokenized or allow the input string to be altered. The fact that the string is altered is the main reason that I don't like strtok. For most applications copying a string is no big deal (my function pretty much did that) but there are times when you will be dealing with a large string and copying it isn't really an option.

I guess you are right: "To each their own."