Random Numbers

[Steven M Hunt]

I am trying to create one of those tip dialog boxes for my program and I want C++ to show random tips. Can I get C++ to "pick" a number in a range of numbers? I know how to do that in JavaScript but that doesn't help me much here. -- Steve

[Nish Nishant]

This might help a little :-

int _tmain(int argc, _TCHAR* argv[])
{
//display 10 numbers between 0 and 9
srand(time(NULL));
for(int i=0; i<10; i++)
{
int r = (int)(((double)rand()/(double)RAND_MAX) * (double)10);
printf("%d\r\n",r);
}
return 0;
}

Regards, Nish

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Author of the romantic comedy Summer Love and Some more Cricket [New Win] Review by Shog9 Click here for review[NW]

[Steven M Hunt]

That line of code you gave me keeps returning 0 and just using the rand() function keeps returning 41. Isn't that strange? -- Steve

[Paul M Watt]

SteveBob wrote: just using the rand() function keeps returning 41. Isn't that strange? It will always return the same sequence of numbers because rand() is a psuedo-random number generator. The way you can get around this problem is by seeding the number generator the first time you use it with a value that always changes, like the current time. Try something like this:

srand(time());

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Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

[Nish Nishant]

SteveBob wrote: That line of code you gave me keeps returning 0 Weird. I got outputs like :- 6 0 9 8 9 2 0 5 8 7 and 6 8 8 7 1 2 0 8 9 8 Regards, Nish p.s. please copy/paste the code exactly and try again!

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Author of the romantic comedy Summer Love and Some more Cricket [New Win] Review by Shog9 Click here for review[NW]

[Nish Nishant]

Paul Watt wrote: Try something like this: srand(time()); The code snippet I gave him already does that! I think he didn't copy/paste it properly. Nish

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Author of the romantic comedy Summer Love and Some more Cricket [New Win] Review by Shog9 Click here for review[NW]

[Steven M Hunt]

Thanks! That fixed the problem! -- Steve

[devvvy]

i've taken so much from the forum and i just finished a module: it's time for me to do one good deed =) call srand, then rand. Quote MSDN: /* RAND.C: This program seeds the random-number generator * with the time, then displays 10 random integers. */ #include #include #include void main( void ) { int i; /* Seed the random-number generator with current time so that * the numbers will be different every time we run. */ srand( (unsigned)time( NULL ) ); /* Display 10 numbers. */ for( i = 0; i < 10;i++ ) printf( " %6d\n", rand() ); } norm

[Sean_Yang]

If I want to get 1, 2 and 3 with EXACT 1/3 chance, how can I do it? int choice; srand(time(NULL)); while(1) { choice= rand() MOD 3; ..... } is there any better method? Thanks Sean