Arduino circuit with tactile button and 10kohm resistor to control build-in LED

button_led.c

#include <avr/io.h>
#include <stdio.h>
#include <util/delay.h>

int main(void) {
  DDRB = 0xFF;        // set all pins on PORTB to output
  DDRD &= ~(1 << 1);  // set pin 2 on PORTD to input
  for (;;) {
    if ((PIND & (1 << 1))) {  // if 2nd bit set on PIND
      PORTB |= (1 << 5);      // turn on LED
    } else {
      PORTB &= ~(1 << 5);  // turn off LED 
    }                                                                                                                                                                    
  }                                                                                                                                                                      
}