++
int age[] = { 25, 21, 23, 30 } ;

void setup() {
  Serial.begin(9600);// initialize serial monitor
  
 Serial.println(age[1]);// print value of age at index 1 (prints 21)
 Serial.println(age[0]);// print value of age at index 0 (prints 25)
 Serial.println(age[2]);// print value of age at index 2 (prints 23)
 Serial.println(age[3]);// print value of age at index 3 (prints 30) 
 Serial.println("=============");   
 
 age[1] = 42;
 age[3] = 22;
 age[0] = 18;
 age[2] = 20; 

 Serial.println(age[1]);// print value of age at index 1 (prints 42)
 Serial.println(age[0]);// print value of age at index 0 (prints 18)
 Serial.println(age[2]);// print value of age at index 2 (prints 20)
 Serial.println(age[3]);// print value of age at index 3 (prints 22)   
 Serial.println("============="); 
 // Defining an empty array for 4 values.
 // age[] has been used above so we cannot redefine it.
 // We must use a new name. I am using marks.
 float marks[4];// 
 marks[0]= 49.5;
 marks[1]= 45.7;
 marks[2]= 36.2;
 marks[3]= 40.7; 
  
 Serial.println(marks[1]);// print value of marks at index 1 (prints 45.7)
 Serial.println(marks[0]);// print value of marks at index 0 (prints 49.5)
 Serial.println(marks[2]);// print value of marks at index 2 (prints 36.2)
 Serial.println(marks[3]);// print value of marks at index 3 (prints 40.7)     
}

void loop() {
    

}