Data input via serial UART

I am building a small project where I need to test performance under different conditions, I want to be able to change a integer value in my sketch by inputting the value on the laptop connected via the UART. I have written this;

char c;
void setup() {
 Serial.begin(9600);
}
void loop() {
if (Serial.available())
{
  c = Serial.read();
}
Serial.println(c); //for testing
delay(500);  //for testing
}

Which seems to work, and holds the numbers 1 - 9 OK as a Char, however I need this number as a integer to integrate into other calculations. Is there an easy way to either return an integer value instead of Char, or, convert the Char to an int?

or, convert the Char to an int?

int n = c - '0';

For one digit numbers, that works.

PaulS:

or, convert the Char to an int?

int n = c - '0';

For one digit numbers, that works.

Thanks Paul (again!)