i need to read a char from serial and the compose an array of char.
You may want to just capture the individual chacters and form them into a string, which is a fairly simple operation. Below is a very simple example where a string is sent from the serial monitor and captured by the arduino, then sent back to the serial monitor.
// zoomkat 7-30-11 serial I/O string test
// type a string in serial monitor. then send or enter
// for IDE 0019 and later
String readString;
void setup() {
Serial.begin(9600);
Serial.println("serial test 0021"); // so I can keep track of what is loaded
}
void loop() {
while (Serial.available()) {
delay(2); //delay to allow byte to arrive in input buffer
char c = Serial.read();
readString += c;
}
if (readString.length() >0) {
Serial.println(readString);
readString="";
}
}