#include <stdio.h>
#include <stdint.h>

int main(void) {
	uint8_t data[] = {12, 250, 100, 100};
    char buf[128], *pos = buf;
    for (int i = 0 ; i != 4 ; i++) {
        pos += sprintf(pos, "%02x", data[i]);
    }
    printf("%s\n", buf);
	return 0;
}