programing

Using Arduino Programming Questions
1

i hava uploaded this program on my arduino uno r3
void setup()
{
Serial.begin(9600);
}
void loop(){
if(Serial.available()>0)
{
int val = (Serial.read()-('0'));
Serial.println(val);
}
}
when i type 1 it prints to me 1
-38

2

When you type '1', you send the code 49 (0x31) to the Arduino.
You're also sending "line feed" (LF, or 0x0A).
Change the "line ending" setting on the serial monitor to "none"

3