How to generate a random number in C++?

[Eddie]

say if i have an integer called number, how to get a random value for it when every time i access it?
int number = ???? ;

[Andy]

#include <cstdlib>
int number;
...
number =rand();//Whenever you need a random int

[Eddie]

does the random number generated in this way have a bound?
... ...
and some how my rand() always give me 41 :smt102

[Andy]

does the random number generated in this way have a bound?
It's compiler-dependent. rand() will give you the posite range of int i.e [0,32767]
and some how my rand() always give me 41 :smt102 You need to do a Built-All after you chance your code (Ctrl-F11)
Also, to prevent the same number generated,use srand()
//Program uses time function to seed random number generator
//and then generates random number
#include <cstdlib>
#include <ctime>
#include <iostream>

using namespace std;

int main()
{
srand((unsigned)time(NULL));
int d=rand()%12;
cout<<d;
}
More about random generators in C++ here (http://www.daniweb.com/techtalkforums/thread1769.html)
In general, you can google for much of the info you are after. It's more time effective.

[Eddie]

I read abou the part on this To generate a random number we use the rand() function. This will produce a result in the range 0 to RAND_MAX, where RAND_MAX is a constant defined by the implementation.

Could not quite make sense of the part on setting the RAND_MAX, so to translate that into actual code, how to generate a rand between say 1-100, which means need to set RAND_MAX???

[Andy]

Could not quite make sense of the part on setting the RAND_MAX, so to translate that into actual code, how to generate a rand between say 1-100, which means need to set RAND_MAX???
RAND_MAX is system dependent and is located within <stdlib.h> for C and <cstdlib> for C++. Determining its value is simple, just do
cout <<RAND_MAX<<endl;
Most likely, you will see 32767 as output. So, you can't change RAND_MAX.
You have the same 41 every time you run rand() because it uses the same seed (srand() initiates that seed). Put it in a for loop to get different numbers.
To generate 1-100, use this
#include <cstdlib>
#include <ctime>
#include <iostream>
using namespace std;

int main()
{

int j;
const int N = 100;

// Set initial seed
srand( (unsigned)time( NULL ) );

for (int i = 0; i < 5; i++) {
j = (int) N * rand() / (RAND_MAX + 1.0);
cout << j << endl;
}

return 0;
}

[Eddie]

why is it not possible to overwrite or redefine constant RAND_MAX to other values?

[Andy]

why is it not possible to overwrite or redefine constant RAND_MAX to other values?You can. How? Rewrite the C++ compiler.
It's not how the compiler defines some system global CONST, it's how you implement your code to achieve the desired goal.

[RussianMike]

srand doesnt seem that random to me (I've used this with implementation of normal distrib) lots of stuff on the net. Any good advice about generating the actual random number?