About Arrays in Arduino I have a question about arrays in Arduino. Sorry for my bad English.
I want to put numbers in an array, and I think the code below works properly.

However, it doesn't work and corrupted numbers show up in the Serial monitor. Even delay(1000) doesn't work.

If I change ND_MAC[i]=128; to "ND_MAC[i]=126;", it works properly. So I'm wondering if this array is char type, but I designate int to array.
How to solve it?

int ND_MAC[7];
char i=0;
void setup() {
  Serial.begin(9600);
}
void loop() {
  for(i=0;i&lt;8;i++){
    ND_MAC[i]=128;
    Serial.print(ND_MAC[i],HEX);
  }
  Serial.println();
  delay(1000);
}
For an array of size 7, the indexes start from 0 (ND_MAC[0]) and end at 6 (ND_MAC[6]) as @MikaelPatel commented. 

So the solution to your issue would be changing the condition in for loop to

for(i=0;i&lt;7;i++) //Changed 8 in your code to 7


Here, the loop iterates from i = 0 to 1 &lt; 7 (i.e., till 6)
and it should work. :)