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random function question

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Deamon:
Hi folks,

under Borland i used the:

randomize();
random(9);

to get a random value betwin 0 and 9 but when i try to compile it under WingW i realize again that it's not ansi compliant. Now my question is how can i achieve the same results in an ansi compliant way ?

regards,
Deamon

takeshimiya:
C version:

--- Code: (cpp) ---#include <stdlib.h>
#include <stdio.h>
#include <time.h>

srand(time(NULL));
int i;
for(i = 0; i < 10; i++)
    printf("Random number #%d: %d\n", i, rand());

--- End code ---

C++ version:

--- Code: (cpp) ---#include <cstdlib>
#include <iostream>
#include <ctime>

std::srand(std::time(0));
for(int i = 0; i < 10; i++)
    std::cout << "Random number #" << i << ": " << std::rand() << std::endl;

--- End code ---

The function srand() is used to seed the random sequence generated by rand(). For any given seed, rand() will generate a specific "random" sequence over and over again.

TDragon:
In addition to Takeshi's helpful post (neither of your samples will compile, Takeshi :?), allow me to add this:


--- Code: (cpp) ---#include <stdlib.h> // if using C++, #include <cstdlib>; may not be necessary in C
#include <time.h> // if using C++, #include <ctime>

// Seed the RNG
srand(time(0));

int RandomIntInRange(int low, int high)
{
return (int)(rand() / (RAND_MAX / (double)(high - low))) + low;
}


--- End code ---
There's probably an unnecessary cast in there, but don't disparage my parentheses -- I use them to indicate my thought processes when I come back to the code a few years down the road.

takeshimiya:

--- Quote from: TDragon on April 04, 2006, 12:21:27 am ---In addition to Takeshi's helpful post (neither of your samples will compile, Takeshi :?)

--- End quote ---

Sorry, forgot to add #include <time.h> for the first example.
The second example compiles fine, why do you say it'll not compile?

TDragon:
Because it didn't #include <ctime> at the time I made my post.

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