>>499
#define STX "\x02"
#define ETX "\x03"
sendto(sock, STX "TEST" ETX, 4 + 2, 0, (struct sockaddr *)&addr, sizerof(addr));

#define TEST_WITH_STX_ETX STX "test" ETX
sendto(sock, TEST_WITH_STX_ETX, sizeof(TEST_WITH_STX_ETX) - 1, 0, (struct sockaddr *)&addr, sizerof(addr));

#define MAX_SEND_SIZE 100
char buf[MAX_SEND_SIZE +3];
sprintf(buf, STX "%." MAX_SEND_SIZE "s" ETX", "TEST");
sendto(sock, buf, strlen(buf), 0, (struct sockaddr *)&addr, sizerof(addr));