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Fifo

During the construction of fifo, typically length of buffer may be important.

   1 FiFo<double> fifo(4);               // reserved only (not filled)
   2 fifo.push_back( data_incoming );

An initialised buffer can be important in variaous situation. For example, if you wish to calculate a moving average, you should wait for N (length of buffer) pieces of incoming of data. However, if you initialise the whole buffer as above, you can proceed immediately.

   1 FiFo<double> fifo_initialised(4, initial_value); // reserved and filled
   2 fifo.push_back( next_data );                // set next data
   3 // ...                                                              
   4 // calculate the average here
   5