How to store values from a sensor inside an empty array?

Question

I need to store the value of the distance in the dist array, then calculate the maximun value and print the index associated with this value:

The problem is when starting the nested for inside another for, the servomotor stops working

// Includes the Servo library
#include <Servo.h>

// Array y valores para funcion valor maximo

int max=0;

int angle=0;

int distance=0;

// Defines Tirg and Echo pins of the Ultrasonic Sensor

const int trigPin = 10;

const int echoPin = 11;

// Variables for the duration and the distance

long duration;

//int distance[180];

Servo myServo1; // Creates a servo object for controlling the servo motor

void setup() {

  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output

  pinMode(echoPin, INPUT); // Sets the echoPin as an Input

  Serial.begin(9600);

  myServo1.attach(12); // Defines on which pin is the servo motor attached
  }

void loop() {

distance = calculateDistance();
  if (distance <= 15 && distance >=2)
  {

  // rotates the servo motor from 1 to 179 degrees and calculate the distance at each angle

  for(int j=90;j>=0;j--){

  myServo1.write(j);

  delay(30);}


  for(int j=0;j<=180;j++){  

  myServo1.write(j); 

  int i=0; 

  int  dist [i] = {calculateDistance()};

      for (i=0;i=180;i++){           <--------------------------------------

       if (dist[i]>max){
      max=dist[i];
      angle=i;
      Serial.print(angle);
      delay(30);}

  }
      }

  // Repeats the previous lines from 179 to 90 degrees

for(int j=180;j>90;j--){  

  myServo1.write(j);

  delay(30);

  }
}
}

// Function for calculating the distance measured by the Ultrasonic sensor
int calculateDistance(){ 

  digitalWrite(trigPin, LOW); 

  delayMicroseconds(2);

  // Sets the trigPin on HIGH state for 10 micro seconds

  digitalWrite(trigPin, HIGH); 

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH); // Reads the echoPin, returns the sound wave travel time in microseconds

  distance= duration*0.034/2;

  return distance;

}

Answer 1

  int i=0; 
  int  dist [i] = {
    calculateDistance()      };

I'm not sure what you are thinking here, but you obviously cannot store data into a zero-length array. You also cannot put a function call to populate an array of variable length.

You need to decide how many elements you need in the array, in advance, and allocate an array of that size.

---

Maybe more like this:

 int  dist [180];

  for (i=0;i<180;i++){    
    dist [i] = calculateDistance ();
    if (dist[i]>max){
      max=dist[i];
      angle=i;
      Serial.print(angle);
      delay(30);
    }

  }

---

Also, this is wrong in your code:

for (i=0;i=180;i++){  

You need to test for < 180 here. Your for loop will assign 180 to i and then check to see if it is non-zero, which will always be true.