为什么我不能超载 *操作员

#include <iostream>
#include <string>
using namespace std;

    class sequence{

    public:
    sequence();
    sequence(int x);
    sequence& operator*=(const &left, const &right);
    ~sequence();
    friend istream& operator >>(istream&, sequence&);
    friend ostream& operator <<(ostream&, sequence&);

    void set_num_samples(); //Set no. of samples
    float* value;           //pointer to float variable
    void allocate_memory(); //Allocates memory
    void set_values_array(); //Sets the values of an array
    void check_array_input(float l); //Checks the values of the array
    void reset_input(float j); //Resets the array
    void de_allocate(); //deallocates memory
    int get_num_samples();
    void set_full_array(int x);
    void calculate_full(float array1[], float array2[]);
    void combine_seq_coef(sequence& inputvoltageA); //Combines the passed      in sequence and coefficient
    void combine_seq(sequence& objectcombine, int sample); // combine the sequences

    private:
    int num_samples;          //number of samples in the object sequence


    };
    class FIR{
    public:
    FIR();
    ~FIR();

    private:
    int num_coefficients;       //Number of coefficients in an FIR (filter impulse response)

      };

    //Constructor for each object
    void sequence::set_num_samples() {      //Set_num_sample definition
    cout << "Please enter the number of values in your sequence: n";
    cin >> num_samples;
    if(num_samples < 0){

        cout << "Value entered must be greater than 0 "<< endl;
        cout << "Please enter the value again: " << endl;
        cin >> num_samples;

    }

    };      //ok (stream op)
    void sequence::allocate_memory() {
    value = new float[num_samples]; //Allocated memory for Array.

}; //ok
    void sequence::set_values_array(){   //Set values for array
    int k;
    for(k=0; k<num_samples; k++){

        cout << "Please enter a positive value for element : " << (k+1) << endl;
        cin >> value[k];
        while(value[k] < 0){
            cout << "Enter positive value " << endl;
            cin >> value[k];
        }
    }
    cout << "Values have been assigned successfully! " << endl;
}; //ok

    //Constructor functions
    void sequence::check_array_input(float l) {   //Checks array values.

    cout << endl << "If you would like to check input values, enter 'y' otherwise, enter 'n' to continue..." << endl;
    char check_value;
    cin >> check_value;
    if (check_value == 'y') {
        int i;
        for (i = 0; i < l; i++) {
            cout << "Value no. " << (i + 1) << " is:" << endl;
            cout << value[i] << endl;

        }
    }
    }
    void sequence::reset_input(float j) {   //Reset voltage value and set to 0;
    cout << endl << "If you would like to reset all input values, enter 'y' otherwise, enter 'n' to continue..."
    << endl;
    char check_value2;
    cin >> check_value2;
    if (check_value2 == 'y') {
        int i;
        for (i = 0; i < j; i++) {
            cout << "Value no." << (i + 1) << ": " << value[i];
            value[i] = 0;
            cout << " is set to 0!" << endl;

        }
    }
    }
     void sequence::de_allocate(){
    delete[] value; //De-allocate memory
    num_samples = 0;
    cout << "De-allocation of input array successful, num of samples reset to 0! " << endl;
}
int sequence::get_num_samples(){
    return num_samples;
}
/* void sequence::calculate_full(float array1[], float array2[]){

    int loop;
    for(loop=0; loop<num_samples; loop++){
        cout << "CoefficientA value no: " << (loop+1) << ": " << array1[loop].value[loop] << endl;
        cout << "InputvoltageA value no." << (loop+1) << ": " << array2[loop].value[loop] << endl;
        value[loop] = (array1[loop].value[loop])*(array2[loop].value[loop]);
        cout << "Combined value no. " << (i+1) << ": " << value[loop] << endl;

        cout << "The combined value gives" <<  full[loop] << endl;
    }

}; */
void sequence::set_full_array(int x){
    num_samples = x;

}

void sequence::combine_seq(sequence& object_combine, int sample_num){
    int loop;
    for(loop=0; loop<sample_num; loop++){


    }
};
sequence& sequence::operator*=(const &left, const &right){

    int y = left.get_num_samples();
    int x;
    for (x=0; )
    sequence = left.value * right.value
    return sequence;
}
sequence::sequence(){    //SEQUENCE CONSTRUCTOR
    set_num_samples();
    allocate_memory();
    set_values_array();
    check_array_input(num_samples);
    reset_input(num_samples);
    de_allocate();
    cout << endl << "Constructor complete!" << endl;
};
sequence::sequence(int a){ //sequence constructor 2
    set_full_array(a);
    allocate_memory();
}

/* sequence::sequence(int a){
    set_full_samples();
    allocate_memory();
    int i;
    for(i=0; i<num_samples; i++){
        cout << "CoefficientA value no: " << (i+1) << ": " << coefficientA().value[i] << endl;
        cout << "InputvoltageA value no." << (i+1) << ": " << inputvoltageA.value[i] << endl;
        cout << "Combined value no. " << (i+1) << ": " << value[i] << endl;
    }
}
 */



sequence::~sequence(){          //Destructor

    cout << "Destructor is called" << endl;

}; //destructor

int main(){
    // Create object, constructor called
    // Constructor calls, set_num_sample, allocate_memory, set_values_array
    // Enters values for voltage Inputs to the sequence into an array
    // Checks values of the array
    // Asks user if they want to reset values and set num samples = 0.

    do {
        cout << "Press the Enter key to continue:" << endl;
    } while (cin.get() != 'n');
    cout << "Input voltage sequence created!" << endl;
    sequence inputvoltageA;
    cout << endl << "CoefficientA sequence created!" << endl;
    sequence coefficientA;
    //Combines sequence and coefficients
    cout << "If you would like to combine the coefficients with the input sequence A enter 'y', otherwise enter 'n'" << endl;
    char prompt4;
    cin >> prompt4;
    if(prompt4 == 'y'){
        int x = coefficientA.get_num_samples();
        sequence full(x);
        full = coefficientA*inputvoltageA;
    }


    /* Ask the user if they want to create new object
     cout << "If you would like to create a new input voltage sequence enter 'y', otherwise enter 'n'" << endl;
     char prompt3;
     cin >> prompt3;
     if(prompt3 == 'y'){
     sequence inputvoltageB;
     }

     cout << "CoefficientA sequence created!" << endl;
     sequence coefficientB;

     */

    /*
     cout << "If you would like to combine this sequence with the sequence before enter 'y', otherwise enter 'n'" << endl;
     char prompt5;
     cin >> prompt5;
     if(prompt5 == 'y'){

     combine_seq(inputvoltageA, num_samples);

     } */

    return 0;
}

为什么我不能超负荷 *操作员？编译器给我错误C 必须具有类型的规范符。我的类型说明符是对序列对象的引用...我认为我在班级和外部定义了过载操作员 *正确的功能。