Concatenate two non constant char arrays in Arduino

I have two non constant char arrays. One is "buff" and other is "buffa". I get values in buffa via rf transmitter of other Arduino and I want to append those data to the data inside of buff. Then I will send all data to other Arduino. So I don't want to send two different char arrays. I want to send them all at once as just one array.

I TRIED SPRINTF BUT IT DOESNT WORK.

char buffa[144]; 
    char buff[1000];


void loop() {

  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;

  sprintf(buff,"<status>\n");    



    if (vw_get_message(buf, &buflen)) { // check to see if anything has been received
      int i;
      for (i = 0; i < buflen; i++) {
        buffa[i] = (char) buf[i];  // the received data is stored in buffer

      }
    }


  distance1 = getDistance(initPin1, echoPin1);
  sendData(3, distance1);

  sprintf(buff, "%s", buffa);




delay(5000);
 const char *msg0 = buff;


 vw_send((uint8_t *)msg0, strlen(msg0)); // Send control character 
 vw_wait_tx();

 Serial.print(msg0);

}