int merge_data(char *dest,char *src1, char *src2)
{
    assert(dest);
    assert(src1);
    assert(src2);
    while (*src1) {
        *dest++=*src1++;
    }
    while (*src2) {
        *dest++=*src2++;
    }
    *dest='\0';
    return 0;
}