Cannot see printf working on Arduino Mega 2560 - arduino

Question

I have an Arduino MEGA 2560 using <stdio.h> library. My aim is to connect a wire across an assigned output pin and the assigned input pins using a pull up resistor. I then want to print on the serial monitor which pins are connected. I cannot see anything on my serial monitor with the code below. Can someone please show me what I am doing wrong?
#include <stdio.h>
int main();
void setup()
{
//Use a Jumper wire to connect form each input to each output
DDRE |= (1 << DDE5); //pin 3 (PE5) set as output
DDRG |= (1 << DDG5); //pin 4 (PG5) set as output
PORTF |= (1 << PORTF0), (1 << PORTF1); //Enable internal resistor on PF0 and PF1 input
}
void loop(void)
{
//Solar 1 --- Load xx
PORTE = PORTE & B00100000; //Turn on PE5 an output pin3: Solar1
_delay_ms(100); //Delay
if (~PINF & B00000001); //A0 input: Load1
{
PORTB = PORTB & B01111111; //Turn off Pin 13_LED
printf("Solar 1 --- Load 1\n\r");
}
//Solar 2 --- Load xx
PORTG = PORTG & B00100000; //Make PG5 an output pin4: Solar1
_delay_ms(100); //Delay
if (~PINF & B00000010); //A1 input: Load2
{
printf("Solar 2 --- Load 1\n\r");
}
}```

Answer 1

By using this include it doesn't mean it'll magically start working. On the computer you'll get everything prepared, but in MCU you'll have to setup stdout stream. And in the C++ you can't use FDEV_SETUP_STREAM and you'll have to do it directly.
#include <stdio.h>
FILE mystdout_serial;
int uart_putchar(char c, FILE *) {
Serial.write(c); // or Serial.print(c);
return 0;
}
void initStdout() {
stdout = &mystdout_serial;
mystdout_serial.buf = nullptr;
mystdout_serial.flags = _FDEV_SETUP_WRITE;
mystdout_serial.put = &uart_putchar;
mystdout_serial.udata = nullptr;
}
void setup() {
Serial.begin(115200);
initStdout();
printf("is it working?\n");
}
void loop() {}
Something like this should work..