程序代码：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
double rand_u(double Lower, double Upper);
double pci(double mean, double variance, int n_samples);

int main()
{
    srand((unsigned)time(NULL));

    double mean=0.0,variance,sum=0.0,sum_square_data=0.0,data;
    int n_samples=1;
    mean = sum/n_samples;
    variance = sum_square_data/(n_samples)-mean*mean;

    while (pci(mean,variance,n_samples)>=5)
    {
     data = rand_u(0.0,1.0);
     sum += data;
     sum_square_data += data*data;
     n_samples++;
    }
   

    printf("samples number =%d\n",n_samples);
    printf("sample mean = %lf\n",mean);
    printf("sample variance  = %lf\n",variance );
    printf("percentage confidence interval =%lf \n", pci( mean,variance,n_samples));
return 0;
}


///////////////////////////////////////////////////////////////////////////

double rand_u(double Lower, double Upper)       // 随机0-1
{

 double r=Lower+(rand()/(double)(RAND_MAX+1)*(Upper-Lower));

 return r;
}

double pci(double mean, double variance, int n_samples)
{
  double s=sqrt(variance);
  double percentage_confidence_interval = ((1.96*s)/sqrt(n_samples))*200;
  return percentage_confidence_interval;
}