I have a question about random numbers. How would I make a random number between 1 and 3 and assign it to an integer in C++?

The simple way:

srand((unsigned int) time(0));
int i = rand() % 3 + 1;

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

This is a good method, though it's slower than the [sloppy] method above.

...
//initialization code
time_t t;
srand((unsigned int)time(&t));

...
//to generate a random number (between 1 and 3)
int RandInt = (int)((rand()/(float)RAND_MAX) * 3) + 1;
...

Later,
ZE.


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EDITed for code correction.

Edited by - zealouselixir on February 8, 2002 12:01:46 AM

thx that helped me alot

btw the second method (div by RAND_MAX) is more random then the first method (mod) posted. since the second method uses all the bits versus the first method which only uses the low bits (in this case only 2 bits matter). though in the second method it should look more like:

//initialization code
// dont need to pass a strucr to time, NULL is
// an acceptable parm
srand((unsigned int)time(NULL));

...
//to generate a random number (between 1 and 3)
int RandInt = (int)((rand()/(float)RAND_MAX) * 3) + 1;



Edited by - a person on February 9, 2002 1:25:26 AM

..............................................................................................................................................................................................................................sad

randomNumber = (rand() % (MAX - MIN)) + MIN;

Edited by - evilcrap on February 9, 2002 3:54:16 AM

Evil: no.

int RandInt = (int)((rand()/(float)RAND_MAX) * MAX-MIN+1) + MIN;

That''s as good as it gets for ranged ints.

Later,
ZE.

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If you want better Random number generators, look up
psudo-random number generator c++
on any search engine. There are some much better ones (Mother of all Random, for instance) than what come with C++

"I''ve learned something today: It doesn''t matter if you''re white, or if you''re black...the only color that REALLY matters is green"
-Peter Griffin

  u_long random_org;void InitRNG() {    WSAData wsaData;    WSAStartup(MAKEWORD(1, 1), &wsaData);    hostent* pHE = gethostbyname("www.random.org");    random_org = *((u_long*)pHE->h_addr_list[0]);}const char request_format[] =    "GET http://www.random.org/cgi-bin/randnum?num=1&min=%i&max=%i&col=1 HTTP/1.0\n\n";char random_request[95];int RandomNumber(int min, int max) {    sprintf(random_request, request_format, min, max);    SOCKET sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);    sockaddr_in sin;    sin.sin_family = AF_INET;    sin.sin_addr.s_addr = random_org;    sin.sin_port = htons(80);    connect(sock, (sockaddr*)&sin, sizeof(sockaddr_in));    send(sock, random_request, strlen(random_request), 0);    char response[1024];    recv(sock, response, 1024, 0);    closesocket(sock);    int random_number;    sscanf(strstr(response, "\r\n\r\n") + 2, "%i", &random_number);    return random_number;}void DoneRNG() {    WSACleanup();}  

...sorry

LOL!

Later,
ZE.

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