value=0, data_ptr=0xbffff6c0
array[]={10, 20, 30, 40, 50, }

after value = *data_ptr++;
 value=10, data_ptr=0xbffff6c4
array[]={10, 20, 30, 40, 50, }

after value = (*data_ptr)++;
 value=20, data_ptr=0xbffff6c4
array[]={10, 21, 30, 40, 50, }

after value = *++data_ptr;
 value=30, data_ptr=0xbffff6c8
array[]={10, 21, 30, 40, 50, }

after value = ++*data_ptr;
 value=31, data_ptr=0xbffff6c8
array[]={10, 21, 31, 40, 50, }