Unable to run this code on arduino uno.

i am trying to run this program, however after uploading it
i do not get anything on the serial monitor. it remains blank.
what could be the reason ?
i tried to see if the interrupt was getting triggered somehow, but doesn’t seem that way.
here is the code
edit : i forgot to add, the programs gets uploaded without any issues.

  IR Capture
  Copyright 2012, all rights reserved.
  James M. Eli
  project parts:
    (1) arduino 16MHz
    (1) 38KHz IR receiver
    (1) breadboard
    (3) wires
  IR - Arduino
  SIG - D2

#define IN_PIN 2
#define MAX_CAPTURE 584  // Line number 1
uint32_t now, start, capture[MAX_CAPTURE];
volatile bool flag_complete;
uint16_t i;    // Line number 2 uint8_t to uint16_t Key point of RAWBUF. uint8_t maximum range 255

void setup() {
  flag_complete = false;
  start = 0;
  now = 0;
  i = 0;
  Serial.print("Ready to capture.");
  attachInterrupt(0, IRInterrupt, CHANGE);
//interrupt fires on ir event (rise/fall)
void IRInterrupt() {
  Serial.print("entered interrupt");
  now = micros();
  capture[i++] = now - start;
  start = now;
  if (i >= MAX_CAPTURE) {
    flag_complete = true;

void loop() {
  while (1) {
    if (flag_complete) {
      for (i=0; i < MAX_CAPTURE; i++) {        
        flag_complete = false;

You can’t call serial.print inside of an ISR. You should at least be seeing the “Ready to capture” message after removing the print from the ISR.

i do not get the "ready to capture" message. i thought for some reason the isr is getting triggered. so i added the serial print there to see if it was in fact entering the isr. but good to know that u cant use Serial.print in an isr

i have noticed something, the maximum voltage i am getting is around 4.5 volts(between any of the high pins and ground) and not 5 volts. would this be effecting the program in any way?

#define MAX_CAPTURE 584  // Line number 1
uint32_t now, start, capture[MAX_CAPTURE];

584 * 4 = 2.3 k-bytes RAM.