MegaGlest Forum

Off topic => Off topic => Topic started by: Gabbe on 11 October 2010, 17:34:21

Title: Help generating random numbers (C::B)
Post by: Gabbe on 11 October 2010, 17:34:21

Code: [Select]

#include <iostream>
#include <cmath>
#include <cstdlib>

int main(){
    using namespace std;

    double y;
    y = rand();

    cout << y << endl;

    cin.get();
    return 0;
}

code in c++, sumposed to generate a random number, but it won`t :S

BTW system("pause"); replaced with cin.get(); doesnt work either :(

Title: Re: Help generating random numbers (C::B)
Post by: Yggdrasil on 11 October 2010, 18:02:26

You need to initialize the pseudo-random generator with srand, mostly srand(time(NULL)).

See:
http://cplusplus.com/reference/clibrary/cstdlib/rand/

Title: Re: Help generating random numbers (C::B)
Post by: Gabbe on 12 October 2010, 11:26:14

I think i might have goten a C::B related problem, I tried to run a new program that were supposed to do 5 * 5 * 5.

Code: [Select]

#include <iostream>
#include <cmath>
#include <cstdlib>

int main(){
    using namespace std;

    double rainbow;
    rainbow = pow(5,3);

    cout << rainbow << endl;

    cin.get();
    return 0;
}

No output when it tried to build, but the error log said:

Quote

Process terminated with status 1 (0 minutes, 0 seconds)
0 errors, 0 warnings

-------------- Build: Release in begining functions ---------------

Compiling: main.cpp
mingw32-g++.exe: installation problem, cannot exec `cc1plus': No such file or directory
Process terminated with status 1 (0 minutes, 0 seconds)
0 errors, 0 warnings

Title: Re: Help generating random numbers (C::B)
Post by: Omega on 12 October 2010, 18:01:54

Basically, you have to seed the random numbers. Otherwise its the same "random" number every time. Yggrdasil's link might help.

Title: Re: Help generating random numbers (C::B)
Post by: Gabbe on 12 October 2010, 19:11:32

Not anything i write in C::B works any :(

Title: Re: Help generating random numbers (C::B)
Post by: Omega on 13 October 2010, 01:48:04

C::B is code blocks, right? Code doesn't depend on the compiler really. You're simply doing it wrong.

Title: Re: Help generating random numbers (C::B)
Post by: Gabbe on 13 October 2010, 08:42:13

Build&run?

Yeah, "Code::Blocks"(http://2.bp.blogspot.com/_O-rOxpu66eY/R9P3jgzqW7I/AAAAAAAAABw/6TYnyo8YAFw/s320/Code_Blocks_logo.jpg)

Dev c++ works..