[resolved] reduce number of elements in array ?

Projects Programming
1

Hello,

this certainly simple answer but i'm a bit lost with pointers and C

I have an array with 12 elements and want randomly choose one...
BUT i want only choose one time each element... until all the elements has been choosen.

In an other langage i'll use a copy of my array and splice() each new element choosen from my array's copy...
But in C... i don't know how to do that.

any idea ?

thanks. :*

2

You could maintain a shadow boolean array to see if the number has been chosen before, or simply negate the value in the array, if you're only expecting positive numbers.

3

Thanks very much...

I've tried your shadow array purpose and give the code.

thanks again

int array[] = {0,2,4,6,8,10};
const int arrayLength = sizeof(array)/sizeof(array[0]);
boolean shadowArray[arrayLength];
int t;
int compteur;

void setup() {
  Serial.begin(9600);
  // fill the shadow array
  for (int i=0; i<arrayLength; i++) {
    shadowArray[i] = false;
  }
}

void loop() {
  if (compteur == arrayLength) {
    for (int i=0; i<arrayLength; i++) {
      shadowArray[i] = false;
    }
    compteur = 0;
    Serial.println("reinit shadowArray\n");
  }
  
  do {t= int(random(arrayLength));}
  while (shadowArray[t]);
  
  Serial.println(array[t]);
  shadowArray[t] = true;
  compteur++;
 
  delay(2000);
}