CODEWITHSUNDEEP
c++
user2197060
user2197060

Reputation:

Random number between two range

rand() or qrand() functions generate a random int.

int a= rand();

I want to get an random number between 0 and 1. How I can do this Work?

Upvotes: 5

Views: 4960

Answers (5)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726489

You can generate a random int into a float, and then divide it by RAND_MAX, like this:

float a = rand(); // you can use qrand here
a /= RAND_MAX;

The result will be in the range from zero to one, inclusive.

Upvotes: 8

888
888

Reputation: 3396

Using C++11 you can do the following:

Include the random header: 

#include<random>

Define the PRNG and the distribution:

std::default_random_engine generator; 
std::uniform_real_distribution<double> distribution(0.0,1.0);

Get the random number

double number = distribution(generator);

In this page and in this page you can find some references about uniform_real_distribution.

Upvotes: 6

SceLus
SceLus

Reputation: 1107

Take a module from the random number which will define the precision. Then do a typecast to float and divide by the module.

float randNum(){
   int random = rand() % 1000;
   float result = ((float) random) / 1000;
   return result;
}

Upvotes: 1

Saqlain
Saqlain

Reputation: 17918

#include <iostream>
#include <ctime>
using namespace std;

//
// Generate a random number between 0 and 1
// return a uniform number in [0,1].
inline double unifRand()
{
    return rand() / double(RAND_MAX);
}

// Reset the random number generator with the system clock.
inline void seed()
{
    srand(time(0));
}


int main()
{
    seed();
    for (int i = 0; i < 20; ++i)
    {
        cout << unifRand() << endl;
    }
    return 0;
}

Upvotes: 2

dowhilefor
dowhilefor

Reputation: 11051

Check this post, it shows how to use qrand for your purpose which is afaik a threadsafe wrapper around rand().

#include <QGlobal.h>
#include <QTime>

int QMyClass::randInt(int low, int high)
{
   // Random number between low and high
   return qrand() % ((high + 1) - low) + low;
}

Upvotes: 3

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