In reply to mittal:
So you want the extra data elements to be zero-ed out, instead of keeping the random data (a new requirement not originally mentioned).
You you zero out mon_tran.data a number of ways before executing the for loop shown above. For example
mon_tran.data = new[mon_tran.data.size()];
or you can modify the loop
for(int index=0;index < mon_tran.data.size; index+)
mon_tran.data[index]=index < data_que.size() ? data_que[index] : 0;