Thread: Random variables

I'd really appreciate some help with this.

I don't know how to select a variable at random and use it in a printf statement.

The task is to design code that generates poetry, so I have a selection of adjectives, nouns, adverbs etc. stored as strings. Say I had 3 adjectives, called adj1, adj2, adj3, I want one of these to be randomly selected and printed to the console.

Thanks.

I don't understand how you wanna pull of a poetry generator, but here's how you generate a rand()m number:

Code:

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

int main()
{
  int a;


  srand(time(NULL));
/*the point of seeding is that there's a NEW number generated each
time you start the program*/

  a = rand();


  return 0;
}

Code:

char *adjectives[3] = { "fast", "slow", "green" };
char *nouns[3] = { "fred", "arthur", "jim" };
printf( "%s %s\n", nouns[rand()%3], adjectives[rand()%3] );

why doesn't it make a difference if I declare

char array[2];

or

char *array[2];

?

Originally Posted by Epo

It's a huge difference.

One's an array of characters.
The other's an array of pointers to characters.

An array of characters (in this case of size 2) can hold:

Code:

char array[2] = {'A', 'B'};

An array of pointers to characters can hold:

Code:

char *array[2] = {"My First String", "My Second String"};

thx for clearing up that one. quite important indeed

Originally Posted by Epo

It's a huge difference.

One's an array of characters.
The other's an array of pointers to characters.

Indeed

An array of characters (in this case of size 2) can hold:

Code:

char array[2] = {'A', 'B'};

An array of pointers to characters can hold:

Code:

char *array[2] = {"My First String", "My Second String"};

I feel the need to elaborate on the above. An array of characters can also be initialised like so:

Code:

/* This is an array of 10 characters that is initialised with
the null terminated character array of "hello", it can be modified */
char array[10] = "hello";

/* This is an array of 6 characters, automatically made just large
enough to fit the null terminated character array of "world", it too
of course can be modified */
char array[] = "world";

/* This is an array of two pointers to char that are initialised to point to a pair
of string literals "hello" and "world".  These strings cannot be modified, but
the pointers could be made to later point to something else.  They do not "hold" 
the strings, just point to them. */
char *array[2] = {"hello", "world"};

Originally Posted by cwr

Indeed




I feel the need to elaborate on the above. An array of characters can also be initialised like so:

Code:

/* This is an array of 10 characters that is initialised with
the null terminated character array of "hello", it can be modified */
char array[10] = "hello";

/* This is an array of 6 characters, automatically made just large
enough to fit the null terminated character array of "world", it too
of course can be modified */
char array[] = "world";

/* This is an array of two pointers to char that are initialised to point to a pair
of string literals "hello" and "world".  These strings cannot be modified, but
the pointers could be made to later point to something else.  They do not "hold" 
the strings, just point to them. */
char *array[2] = {"hello", "world"};

when you say can't be modified on the last one, you can still write to those positions. So where's hte problem? What do you mean with "can be modified"...

that looks quite usefull for when you're working with structs. nice!