Question

How to generate a random double number between min and max in C

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
double GenerateRandomDoubleNumberMinMax(double min, double max) {
    double range = max - min + 1;
     
    return ((double)rand() / RAND_MAX) * range + min;
}
 
int main() {
    srand(time(NULL)); // Seed the random number generator
    double min = 70.0;
    double max = 100.0;
 
    double d = GenerateRandomDoubleNumberMinMax(min, max);
     
    printf("%f\n", d);
     
    return 0;
}

     
/*
run:
  
86.330671
  
*/

 

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Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

double getRandomDouble(double min, double max) {
    return min + drand48() * (max - min);
}

int main() {
    srand48(time(NULL)); // Seed the random number generator
    
    double randomDouble = getRandomDouble(20, 35);
    
    printf("Random double: %f\n", randomDouble);
    return 0;
}

   
   
/*
run:
   
Random double: 30.819647
3.588470
   
*/

 

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