用c语言设计企业员工管理系统程序，要求先以管理员身份登录（自己设定进入密码）。输入密码正确后，录入某企业员工（假定不超过 50人）的工资。密码限定最多输入三次，三次不成功退出系统。将员工工资按照从高到低顺序排序；假定工资超过3500 元的，超出部分按 5%缴税，给出该企业上缴工资税金总数，并统计缴税员工占总员工的比例

很好，这是一个比较典型的企业员工管理系统的需求，我可以给你提供一些思路和代码实现。

1. 设计管理员登录功能

首先，我们需要设计管理员登录功能，可以设置一个固定的密码，最多输入三次机会。如果输入正确，就可以进入员工工资录入界面；如果输入错误三次，就退出程序。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_ATTEMPTS 3 // 最多尝试次数
#define PASSWORD "123456" // 管理员密码

int main()
{
    char password[20];
    int attempts = 0;

    printf("Please enter password to login as administrator:\n");

    while (attempts < MAX_ATTEMPTS) {
        scanf("%s", password);
        if (strcmp(password, PASSWORD) == 0) {
            printf("Login successful!\n");
            break;
        } else {
            attempts++;
            printf("Incorrect password, please try again.\n");
        }
    }

    if (attempts == MAX_ATTEMPTS) {
        printf("Too many attempts, exit program.\n");
        exit(1);
    }

    // TODO: 进入员工工资录入界面

    return 0;
}

2. 录入员工工资

登录成功后，我们就可以进入员工工资录入界面。由于假设员工不超过50人，我们可以使用一个数组来存储员工的工资信息。

#define MAX_EMPLOYEES 50 // 最多员工数

struct Employee {
    char name[20];
    float salary;
};

struct Employee employees[MAX_EMPLOYEES];
int count = 0; // 当前员工数

void input_employee_info()
{
    printf("Please input employee information (name salary):\n");
    printf("(Press Enter to exit input)\n");

    while (count < MAX_EMPLOYEES) {
        scanf("%s", employees[count].name);
        if (strlen(employees[count].name) == 0) {
            break;
        }
        scanf("%f", &employees[count].salary);
        count++;
    }
}

3. 排序员工工资

录入员工工资后，我们需要按照从高到低的顺序对员工工资进行排序。可以使用快速排序算法来实现。

void swap(struct Employee *a, struct Employee *b)
{
    struct Employee tmp = *a;
    *a = *b;
    *b = tmp;
}

int partition(struct Employee arr[], int low, int high)
{
    float pivot = arr[high].salary;
    int i = low - 1;

    for (int j = low; j < high; j++) {
        if (arr[j].salary > pivot) {
            i++;
            swap(&arr[i], &arr[j]);
        }
    }

    swap(&arr[i+1], &arr[high]);

    return i + 1;
}

void quicksort(struct Employee arr[], int low, int high)
{
    if (low < high) {
        int pi = partition(arr, low, high);
        quicksort(arr, low, pi - 1);
        quicksort(arr, pi + 1, high);
    }
}

void sort_employees()
{
    quicksort(employees, 0, count - 1);
}

4. 缴税及统计

按照工资排序后，我们就可以统计缴税信息了。根据题目要求，工资超过3500元的部分需要缴税，缴税比例为5%。统计缴税员工占总员工的比例时，可以使用一个计数器来记录缴税员工的数量。

void calculate_tax()
{
    float total_tax = 0;
    int tax_count = 0;

    printf("Employee salary information (sorted):\n");
    for (int i = 0; i < count; i++) {
        printf("%s: %.2f\n", employees[i].name, employees[i].salary);
        if (employees[i].salary > 3500) {
            float tax = (employees[i].salary - 3500) * 0.05;
            total_tax += tax;
            tax_count++;
        }
    }

    printf("Total tax: %.2f\n", total_tax);
    printf("Tax employee ratio: %.2f%%\n", (float)tax_count / count * 100);
}

5. 完整代码

最后，我们把以上几个部分整合起来，得到完整的企业员工管理系统程序。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_ATTEMPTS 3 // 最多尝试次数
#define PASSWORD "123456" // 管理员密码
#define MAX_EMPLOYEES 50 // 最多员工数

struct Employee {
    char name[20];
    float salary;
};

struct Employee employees[MAX_EMPLOYEES];
int count = 0; // 当前员工数

void input_employee_info()
{
    printf("Please input employee information (name salary):\n");
    printf("(Press Enter to exit input)\n");

    while (count < MAX_EMPLOYEES) {
        scanf("%s", employees[count].name);
        if (strlen(employees[count].name) == 0) {
            break;
        }
        scanf("%f", &employees[count].salary);
        count++;
    }
}

void swap(struct Employee *a, struct Employee *b)
{
    struct Employee tmp = *a;
    *a = *b;
    *b = tmp;
}

int partition(struct Employee arr[], int low, int high)
{
    float pivot = arr[high].salary;
    int i = low - 1;

    for (int j = low; j < high; j++) {
        if (arr[j].salary > pivot) {
            i++;
            swap(&arr[i], &arr[j]);
        }
    }

    swap(&arr[i+1], &arr[high]);

    return i + 1;
}

void quicksort(struct Employee arr[], int low, int high)
{
    if (low < high) {
        int pi = partition(arr, low, high);
        quicksort(arr, low, pi - 1);
        quicksort(arr, pi + 1, high);
    }
}

void sort_employees()
{
    quicksort(employees, 0, count - 1);
}

void calculate_tax()
{
    float total_tax = 0;
    int tax_count = 0;

    printf("Employee salary information (sorted):\n");
    for (int i = 0; i < count; i++) {
        printf("%s: %.2f\n", employees[i].name, employees[i].salary);
        if (employees[i].salary > 3500) {
            float tax = (employees[i].salary - 3500) * 0.05;
            total_tax += tax;
            tax_count++;
        }
    }

    printf("Total tax: %.2f\n", total_tax);
    printf("Tax employee ratio: %.2f%%\n", (float)tax_count / count * 100);
}

int main()
{
    char password[20];
    int attempts = 0;

    printf("Please enter password to login as administrator:\n");

    while (attempts < MAX_ATTEMPTS) {
        scanf("%s", password);
        if (strcmp(password, PASSWORD) == 0) {
            printf("Login successful!\n");
            break;
        } else {
            attempts++;
            printf("Incorrect password, please try again.\n");
        }
    }

    if (attempts == MAX_ATTEMPTS) {
        printf("Too many attempts, exit program.\n");
        exit(1);
    }

    input_employee_info();
    sort_employees();
    calculate_tax();

    return 0;
}