Question

c语言编程问题？

从键盘中输入正整数n，求表达式(1^2)/(1+1)+(2^2)/(2+1)+(3^2)/(3+1)+……＋(n^2)/(n+1)的值。(此处i^2代表i的平方，i从1~n)

Answer 1

#include <stdio.h>

#include <stdlib.h>

struct student {

int num;

char name[20];

float score[4];

};

void input(struct student a[], int);

void aver(struct student a[], int,struct student b[]);

void order(struct student a[], int);

void output(struct student a[], int,struct student b[]);

int main() {

struct student stu[100];

struct student b[100];

int n;

printf("请输入学生个数:");

scanf("%d", &n);

input(stu, n);

aver(stu, n,b);

order(stu, n);

output(stu, n,b);

return 0;

}

void input(struct student a[], int n) {

int i, j;

// printf("请输入学生的学号，姓名，英语，数学，物理，语文成绩:\n");

for (i = 0; i < n; i++) {

printf("请输入第%d个学生的学号，姓名，英语，数学，物理，语文成绩:\n", i + 1);

scanf("%d", &a[i].num);

//gets(a[i].name);

scanf("%s", &a[i].name);

for (j = 0; j < 4; j++)

scanf("%f", &a[i].score[j]);

}

}

void aver(struct student a[], int n,struct student b[]) {

int i=0, j;

for (i = 0; i < n; i++) {

b[i].score[0] = 0;

for (j = 0; j < 4; j++)

b[i].score[0] += a[i].score[j];

b[i].score[0] = b[i].score[0] / 4;

}

}

void order(struct student a[], int n) {

int i, j;

struct student t[1];

for (i = 1; i < n; i++)

for (j = 0; j < n - i; j++)

if (a[j].score[3] < a[j + 1].score[3]) {

t[1] = a[j];

a[j] = a[j + 1];

a[j + 1] = t[1];

}

}

void output(struct student a[], int n,struct student b[]) {

int i, j;

printf("学号\t姓名\t  英语\t  数学\t  物理\t  语文\t  平均成绩如下:\n");

for (i = 0; i < n; i++) {

printf("%d\t%s\t", a[i].num, a[i].name);

for (j = 0; j < 4; j++)

printf("%.2f\t", a[i].score[j]);

printf("%.2f", b[i].score[0]);

printf("\n");

}

}

帮你改了一些，看看测试：

Answer 2

#include<stdio.h>

int main()

{ int i,n;

  double sum=0;

  scanf("%d",&n);

  for(i=1; i<=n; i++)

    sum+=i*i*1.0/(i+1);

  printf("%f\n",sum);

  return 0;

}

Answer 3

#include<stdio.h>
void main( )
{
int i,n;

float sum=0;

scanf("%d",&n);
for(i=1;i<=n;i++)

sum+=i*i/(i+1);

printf("sum=%f",sum);

return 0;

}