평균이랑 표준편차 구하는데요 표준편차는 잘 뜨는데 평균이 자꾸 0으로 떠요...왜이러죠??



#include <iostream>

#include <cmath>

using namespace std;

float standard_deviation(float data[], int n);

float mean;


float standard_deviation(float data[], int n)

{

    float mean=0.0, sum_deviation=0.0;

    int i;

    for(i=0; i<n;++i)

    {

        mean+=data[i];

    }

    mean=mean/n;

    for(i=0; i<n;++i)

    sum_deviation+=(data[i]-mean)*(data[i]-mean);

    return sqrt(sum_deviation/n);           

}


int main()

{

    int n, i;

    float data[100];

    cout << "Enter number of students : ";

    cin >> n;

    for(i=0; i<n; ++i)

{

cout << "Enter score of student "<<(i+1)<<" : ";

cin >> data[i];

}

cout << "Average score: "<<mean<<endl;

    cout << "standard deviation : " << standard_deviation(data,n)<<endl;

    return 0;

}