How to generate random floating point numbers from 0 to 1 [duplicate] - c

Question

This question already has answers here:
How to generate random float number in C
(6 answers)
Random float number generation
(14 answers)
Generate random between [0, 1)
(2 answers)
Closed 5 years ago.
I have found a code in this answer How to generate a random integer number from within a range a code that works perfectly, but tis is for integers. Does anybody know how can I change this code so it returns uniformly a number between 0 and 1?
#include <stdlib.h> // For random(), RAND_MAX
// Assumes 0 <= max <= RAND_MAX
// Returns in the closed interval [0, max]
long random_at_most(long max) {
unsigned long
// max <= RAND_MAX < ULONG_MAX, so this is okay.
num_bins = (unsigned long) max + 1,
num_rand = (unsigned long) RAND_MAX + 1,
bin_size = num_rand / num_bins,
defect = num_rand % num_bins;
long x;
do {
x = random();
}
// This is carefully written not to overflow
while (num_rand - defect <= (unsigned long)x);
// Truncated division is intentional
return x/bin_size;
}

Answer 1

You really don't need all that complicated code there. Imagining you initialized your pseudo-random number generator correctly in your main function, with for instance something like this for rand:
srand(time(NULL));
The following code should be enough:
double random(){
return (double)rand()/RAND_MAX;
}
The idea there is just to pick a random number between 0 and RAND_MAX, and then to divide it by RAND_MAX. As RAND_MAX/RAND_MAX is equal to 1, you will return a random value between 0 and 1.

Answer 2

The C way:
#include <stdlib.h>
int main(int argc, char** argv)
{
printf("Random value: %f\n", (float) rand() / (float) RAND_MAX);
return 0;
}
The C++11 way:
#include <random>
int main(int argc, char** argv)
{
std::default_random_engine generator;
std::uniform_real_distribution<float> distribution(0.0, 1.0);
printf("Random value: %f\n", distribution(generator));
return 0;
}