Problem with Random Integer in C Robotics

Okay, so basically, I’m trying to have my robot go forwards, until it detects a wall, then reverse, and then turn into a random direction. Problem is, it’s only turning right. If anyone can help with this, I will be VERY appreciative, because I’ve spent about two days on it, and not even my teacher can figure out what’s wrong with it. It is more of a robotics thing rather than just a code thing, but you can probably just ignore the motor/servo jargon. Thanks!

#include <PRIZM.h> // include PRIZM library
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define RAND_MAX 1
PRIZM prizm;            // instantiate a PRIZM object “prizm” so we can use its functions
    
void setup() {
    
  prizm.PrizmBegin();   //initialize PRIZM
  prizm.setServoSpeed(1,50);
  prizm.setMotorInvert(1,1);      // invert the direction of DC Motor 1
  // to harmonize the direction of
  // opposite facing drive motors
}
    
void loop() {
  int x;
  x = 1;
  int r;
  while((prizm.readSonicSensorCM(3) > 50)&&(x == 1))
    {
      prizm.setMotorPowers(40,40);    // if distance greater than 25cm, do this
      prizm.setServoPosition(1,146.75);
      prizm.setServoPosition(2,55.5);
      r = rand();
        
    }
  if((prizm.readSonicSensorCM(3) <= 50)||(x == 0))
    {
      x--;
      prizm.setServoPosition(1, 54.5);
      prizm.setServoPosition(2,145.25);
      prizm.setMotorPowers(0,0);
      delay(250);
      prizm.setMotorPowers(-30,-30);   
      delay(750);
      prizm.setMotorPowers(0,0);
      delay(300);
      if (r == 0) {
        prizm.setMotorPowers(-50,50);
        delay(1100);
      }
      else {
        prizm.setMotorPowers(50,-50);
        delay(1100);
      }
      prizm.setMotorPowers(0,0);
      delay(200);
      x++;
    }   
}

>Solution :

Note that your redefinition of RAND_MAX has no effect on the output of the rand() function. This is not a parameter for the function, but a constant telling you what the maximum value of the output is.

The best way to get a 50% of probability in your if (r == 0), is to go one side if r is even, the other if it is odd:

if ((r % 2) == 0) {
  prizm.setMotorPowers(-50,50);
  delay(1100);
 }
 else {
   prizm.setMotorPowers(50,-50);
   delay(1100);
 }