C语言中求和、计算平均值、方差和标准差

计算C语言中的求和、标准差、方差和标准差等，需要加上头文件：#include

#include
#include "math.h"

    double sum = 0;//求和
    double array[4] = {1.2,2.1,3.1,4.1};
    int length = 0;//数组长度
    double average = 0;//求平均数
    double var = 0; //求方差
    double standard = 0; //求标准差

    int main()
    {
        for (int i = 0; i <= 3;i++)
        {
            sum += array[i];//求和
        }

        length = sizeof(array) / sizeof(array[0]);//求数组长度
        average = sum / length;//求平均值
 
        for (int j = 0; j <= 3;j++)
        {
            var += pow(array[j]-average,2)/length;//求方差
        }
    
        standard = pow(var,0.5);//求标准差
   
        printf("sum = %g\n",sum);//这边打印也可以使用printf("%f\n",sum);这种打印默认出来的数是小数点后6位
        printf("length of array[4] = %d\n",length);
        printf("average = %g\n",average);
        printf("var = %g\n",var);
        printf("standard = %g\n",standard);
        while (1);
        return 0;
    }