c++ create a random decimal between 0.1 and 10
13,367
Solution 1
The C++11 way:
#include <random>
std::random_device rd;
std::default_random_engine generator(rd()); // rd() provides a random seed
std::uniform_real_distribution<double> distribution(0.1,10);
double number = distribution(generator);
If you only want integers, use this distribution instead:
std::uniform_int_distribution<int> distribution(0, x);
C++11 is really powerful and well-designed in this respect. The generators are separate from the choice of distribution, ranges are taken into account, thread safe, performance is good, and people spent a lot of time to make sure it's all correct. That last part is harder to get right than you think.
Solution 2
srand (time(NULL));
seed = ((double)rand()) / ((double)RAND_MAX) * 9.9 + 0.1;
To show up to 2 decimal places:
printf("%.2lf\n", seed);
If the x
you need is smaller than RAND_MAX
, then use
seed = rand() % (x+1);
to generate an integer in [0, x]
.
Author by
tmacnadidas
Updated on June 05, 2022Comments
-
tmacnadidas almost 2 years
How would I do this?
This is my attempt of doing so:
srand (time(NULL)); seed = ((double)rand()) / ((double)RAND_MAX) * 10 + 0.5;
Also what is the way of creating a random integer between 0 and some int x. [0,x]