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#2
rjsp2020-10-14 17:10
改掉数个错误及不好的地方
 程序代码：#include <stdio.h> int main( void ) { FILE* fp = fopen("D:\\data.txt","r"); if(fp == NULL) { printf("文件打开失败!\n"); return 1; } puts( "读取数据：" ); size_t k = 0; float sum=0.0f, sum2=0.0f; for( float x; fscanf(fp,"%f",&x)==1; ++k ) { sum2 += x*x; sum += x; printf( "%.0f ", x ); } fclose( fp ); puts( "\n=======================================" ); float avr = sum / k; float fc = (sum2 - sum*sum/k)/(k-1); printf(" 读取个数：%d\n",k); printf(" 平 均 值：%.2f\n",avr); printf(" 方 差：%.2f\n",fc); } |
程序代码：// 从文本文件"data.txt"中取出数据，并计算平均值，方差
#include<stdio.h>
#include <math.h>
#define hh printf("\n=======================================\n");
void main()
{
FILE *fp;
float x,avr,fc,a[520],sum = 0.0;
int i,k = 0;
fp = fopen("D:\\data.txt","r");
if(fp == NULL)
{
printf("文件打开失败!\n");
}
else
{
printf("读取数据：\n");
fscanf(fp,"%f",&x);
while(!feof(fp))
{
a[k++] = x;
printf("%.0f ",x);
sum += x;
fscanf(fp,"%f",&x);
}
/* fscanf(fp,"%f",&x);
a[k++] = x;
printf("%.0f ",x);
sum += x; */
avr = sum / k; // k 为读到的数据个数
sum = 0;
for(i = 0;i < k;i++)
{
sum += (a[i] - avr) * (a[i] - avr);
}
fc = sum / (k - 1);
hh
printf(" 读取个数：%d\n",k);
printf(" 平 均 值：%.2f\n",avr);
printf(" 方 差：%.2f\n",fc);
}
hh
fclose(fp);
}