Help me get an a in c programming

[Ex-RoNiN 0]

Right, as we all know the standard rand() function in C will spit out random numbers in the region of 0 to n, where n is machine dependent. I think its 32 thousand and something for 32 bit machines.

Now, I need the random number generator so I can imitate some very primitive AI in my game that I have to write for my C class However, I need it to generate (randomly) either 0, 1 or 2.

This value will then be used in a switch statement etc. But the thing I need to know is: how do I tell the rand() function to find me random values from 0-2 Obviously just int's please

Oh, and does someone know some good programming message boards, I had a look on google but couldn't find anything decent

Cheers in advance mates

[Sheriff 0]

Gamedev.net

Pretty good message boards and articles covering aspects of AI, OpenGL, DirectX, Networking etc.

Also checkout Flipcode.com

[TimNiceButDim 0]

You are coding in C!!! I hope to god I never have to learn any of that in my life time. For a student rasied on JAVA, C++ is beastly enough!! I presume something like this this will work in C.

Taken from www.cplusplus.com:

/* rand example */

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

int main ()

{

/* initialize random generator */

srand ( time(NULL) );

/* generate some random numbers */

printf ("A number between 0 and RAND_MAX (%d): %d\n", RAND_MAX, rand());

printf ("A number between 0 and 99: %d\n", rand()%100);

printf ("A number between 20 and 29: %d\n", rand()%10+20);

return 0;

}

So basically you use the mod (%) operator (returns an int). rand()%3 should give you something between 0 - 2 inclusive.

srand ( time(NULL) ); seeds the number generator with the current system time and methinks it's general good practice. Dunno how this works in C though.

Tim!

[Ex-RoNiN 0]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (TimNiceButDim @ April 14 2002,19:16)</td></tr><tr><td id="QUOTE">You are coding in C!!! I hope to god I never have to learn any of that in my life time. For a student rasied on JAVA, C++ is beastly enough!! I presume something like this this will work in C.

Taken from www.cplusplus.com:

/* rand example */

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

int main ()

{

 /* initialize random generator */

 srand ( time(NULL) );

 /* generate some random numbers */

 printf ("A number between 0 and RAND_MAX (%d): %d\n", RAND_MAX, rand());

 printf ("A number between 0 and 99: %d\n", rand()%100);

 printf ("A number between 20 and 29: %d\n", rand()%10+20);

 return 0;

}

So basically you use the mod (%) operator (returns an int). rand()%3 should give you something between 0 - 2 inclusive.

srand ( time(NULL) ); seeds the number generator with the current system time and methinks it's general good practice. Dunno how this works in C though.

Tim!<span id='postcolor'>

Ahhhhhh, now I know what was amiss!

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Code Sample </td></tr><tr><td id="CODE">#include <time.h><span id='postcolor'>

I didn't have that library included, and that caused the compiler to moan about

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Code Sample </td></tr><tr><td id="CODE">srand (time(0))<span id='postcolor'>. In particular, it moaned about time not being declared.

So I just put </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Code Sample </td></tr><tr><td id="CODE">srand (3) <span id='postcolor'>, which in combination with </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Code Sample </td></tr><tr><td id="CODE">rand () % 3<span id='postcolor'> would create a random sequence of numbers (if put in a loop), but not genuinely random numbers for every "step" in that sequence (ie u always get 20120012211).

Thank you very much

[Guest]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Ex-RoNiN @ April 14 2002,18:07)</td></tr><tr><td id="QUOTE">I think its 32 thousand and something for 32 bit machines.<span id='postcolor'>

A bit is 0 or 1. 32 bit is therefore 2^32 = 4294967296

which is 4,3 billion (4,3 * 10^9).

[Ex-RoNiN 0]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (denoir @ April 15 2002,01:08)</td></tr><tr><td id="QUOTE">7--></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Ex-RoNiN @ April 14 2002,187)</td></tr><tr><td id="QUOTE">I think its 32 thousand and something for 32 bit machines.<span id='postcolor'>

A bit is 0 or 1. 32 bit is therefore 2^32 = 4294967296

which is 4,3 billion (4,3 * 10^9).<span id='postcolor'>

Never mind, it is not machine dependent anyway, it is compiler dependent.

Silly me