Arduino how to convert int to char array

The code below shows how to convert int to char array in Arduino and how to convert char array to int.

void setup() {

  // Open serial communications and wait for port to open:

  Serial.begin(9600);

  while (!Serial) {

    ; // wait for serial port to connect. Needed for Leonardo only

  }

  // send an intro:

  Serial.println("\n\nString Constructors:");

  Serial.println();

}

String str;

int num = 0;

int num2 = 0;

char cstr[16];

void loop() {

  // int to char array

  delay(200);

  num++;

  str = String(num);

  str.toCharArray(cstr,16);

  Serial.println(cstr);      // prints "Hello String"

  //char array to int

  num2 = atoi(cstr);

  num2++;

  Serial.println(num2); 

}