转载：https://blog.csdn.net/littlehero_121/article/details/98848871

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 <math.h>

#include<stdio.h>
#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;}