#include<stdio.h> int main(void) float n,sum=0; scanf("%d",&n); for(int x = 1;x <= njx++ sum += 1/x; printf("n=%d,sum=%d",n,sum); return 0;
时间: 2024-09-26 09:03:51 浏览: 7
这段代码定义了一个简单的程序,用于计算从1到`n`(用户输入的整数)所有倒数之和。首先,我们分析一下代码:
```c
#include<stdio.h> // 引入标准输入输出头文件
int main(void) {
float n, sum = 0; // 定义两个变量,n存储输入值,sum用于累加倒数
scanf("%d", &n); // 从用户那里读取一个整数并赋值给n
for (int x = 1; x <= n; x++) { // 使用for循环,条件是x小于等于n
sum += 1 / x; // 每次迭代时,将1除以当前x值并添加到总和上
}
printf("n=%d, sum=%f", n, sum); // 输出结果,n为整数值,sum为浮点数
return 0; // 主函数结束,返回0表示正常退出
}
```
**问题**:
1. 代码中的`njx++`应改为`n++;`,因为`njx`未被声明且看起来像是拼写错误。
2. 当输入的n是负数或零时,这个程序会有什么行为?它是否支持这类输入?
3. 如果希望得到更精确的结果,避免除法带来的浮点误差,是否可以使用其他算法?
相关问题
完善下面求平均值的程序 #include <stdio.h>#include <math.h>#include <string.h> void input(Census data[]) { int i; for ( i = 0; i < SIZE; i++) { printf("请输入第 %d 次普查年份: ", i+1); scanf("%d", &data[i].year); printf("请输入第 %d 次普查全国人口数目: ", i+1); scanf("%f", &data[i].population); }} float average(Census data[]) { float sum = 0; int i; for ( i = 0; i < SIZE; i++) { sum += data[i].population; } return sum / SIZE;}
这段程序中,我们需要自己定义一个Census结构体,其中包含年份和人口数目两个成员变量,并且假设程序中已经定义了SIZE常量表示普查的次数。完整的程序如下:
#include <stdio.h>
#include <math.h>
#include <string.h>
#define SIZE 3
typedef struct {
int year;
float population;
} Census;
void input(Census data[]) {
int i;
for (i = 0; i < SIZE; i++) {
printf("请输入第 %d 次普查年份: ", i+1);
scanf("%d", &data[i].year);
printf("请输入第 %d 次普查全国人口数目: ", i+1);
scanf("%f", &data[i].population);
}
}
float average(Census data[]) {
float sum = 0;
int i;
for (i = 0; i < SIZE; i++) {
sum += data[i].population;
}
return sum / SIZE;
}
int main() {
Census data[SIZE];
input(data);
printf("全国人口平均数目为: %.2f\n", average(data));
return 0;
}
#include<stdio.h> #include<stdlib.h> #include<string.h> #include<windows.h> struct stu { int id; char name[10]; float grade[11]; float sum; float average; float gpa; struct stu* next; }stu* head;stu *tail;按照这个结构体来续写C语言代码。要求将学生信息保存在硬盘文件中,通过制定文件路径和文件名称来导入学生信息;按照学号对所有学生信息进行升序、降序排列,并输出到屏幕显示或输出到文件
好的,我会为你续写代码。以下是完整代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>
struct stu {
int id;
char name[10];
float grade[11];
float sum;
float average;
float gpa;
struct stu* next;
};
typedef struct stu stu;
stu* head = NULL;
stu* tail = NULL;
// 读取学生信息
void read_info(char* file_name) {
FILE* fp;
fp = fopen(file_name, "r");
if(fp == NULL) {
printf("Failed to open file %s\n", file_name);
return;
}
while(!feof(fp)) {
stu* s = (stu*)malloc(sizeof(stu));
fscanf(fp, "%d%s%f%f%f", &s->id, s->name, &s->grade[0], &s->grade[1], &s->grade[2]);
s->sum = s->grade[0] + s->grade[1] + s->grade[2];
s->average = s->sum / 3.0;
s->gpa = s->average / 20.0 - 1.5;
if(head == NULL) {
head = s;
tail = s;
tail->next = NULL;
} else {
tail->next = s;
tail = s;
tail->next = NULL;
}
}
fclose(fp);
}
// 写入学生信息
void write_info(char* file_name) {
FILE* fp;
fp = fopen(file_name, "w");
if(fp == NULL) {
printf("Failed to open file %s\n", file_name);
return;
}
stu* p = head;
while(p != NULL) {
fprintf(fp, "%d %s %.2f %.2f %.2f\n", p->id, p->name, p->grade[0], p->grade[1], p->grade[2]);
p = p->next;
}
fclose(fp);
}
// 按照学号升序排序
void sort_by_id_ascending() {
int len = 0;
stu* p = head;
while(p != NULL) {
len++;
p = p->next;
}
p = head;
for(int i = 0; i < len - 1; i++) {
for(int j = 0; j < len - i - 1; j++) {
if(p->id > p->next->id) {
stu* tmp = p->next;
p->next = tmp->next;
tmp->next = p;
if(p == head) {
head = tmp;
} else {
stu* q = head;
while(q->next != p) {
q = q->next;
}
q->next = tmp;
}
p = tmp;
}
p = p->next;
}
p = head;
}
}
// 按照学号降序排序
void sort_by_id_descending() {
int len = 0;
stu* p = head;
while(p != NULL) {
len++;
p = p->next;
}
p = head;
for(int i = 0; i < len - 1; i++) {
for(int j = 0; j < len - i - 1; j++) {
if(p->id < p->next->id) {
stu* tmp = p->next;
p->next = tmp->next;
tmp->next = p;
if(p == head) {
head = tmp;
} else {
stu* q = head;
while(q->next != p) {
q = q->next;
}
q->next = tmp;
}
p = tmp;
}
p = p->next;
}
p = head;
}
}
// 输出学生信息
void print_info() {
stu* p = head;
while(p != NULL) {
printf("%d %s %.2f %.2f %.2f %.2f\n", p->id, p->name, p->grade[0], p->grade[1], p->grade[2], p->gpa);
p = p->next;
}
}
int main() {
char file_name[100];
printf("Please enter the file path and name: ");
scanf("%s", file_name);
read_info(file_name);
printf("Before sorting:\n");
print_info();
sort_by_id_ascending();
printf("After sorting by id in ascending order:\n");
print_info();
sort_by_id_descending();
printf("After sorting by id in descending order:\n");
print_info();
printf("Please enter the file path and name you want to save the sorted information: ");
scanf("%s", file_name);
write_info(file_name);
return 0;
}
```
这个程序可以通过文件读取来导入学生信息,根据学号升序或降序排列学生信息,并输出到屏幕或文件。请注意,在运行程序时,需要输入导入文件的路径和名称,以及希望将排序信息保存到的文件路径和名称。