C -error: expected ';', ',' or ')' before '=' token - c

Question

I need help. It's displaying "error: expected ';', ',' or ')' before '=' token"
at line 5 (at the getRandom method) when i try to build and then run it. I've gone through it several times over and over again and i can't seem to figure out what the problem could be
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
double getRandom (double min = -1, double max = 1) {
return min + (rand() * (max - min) / RAND_MAX);
}
int totalPoints = 0;
int pointsInCircle = 0;
void *countPoints (void *X) {
for (int i = 0; i < totalPoints; i++) {
double X = getRandom();
double Y = getRandom();
if (X*X + Y*Y <= 1)pointsInCircle++;
}
return NULL;
}
int main()
{
srand(time(NULL));
pthread_t thread;
printf ("Enter total points for experiment : ");
scanf ("%d" , totalPoints);
pthread_create(&thread, NULL, &countPoints, NULL);
pthread_join(thread, NULL);
double PI = (4.0 * pointsInCircle) / totalPoints;
printf ("Approximate value for PI for total points %d is: %d " , totalPoints, PI);
return 0;
}

Answer 1

double getRandom (double min = -1, double max = 1) {
return min + (rand() * (max - min) / RAND_MAX);
}
This is not C.
double getRandom (double min, double max) {
return min + (rand() * (max - min) / RAND_MAX);
}
When you call it with no actual arguments in your code
double X = getRandom();
double Y = getRandom();
you should replace these calls with
double X = getRandom(-1, 1);
double Y = getRandom(-1, 1);