用C语言编写工资管理系统软件，职工数据包括:职工号，姓名，基本补贴金额，奖励金额，扣除金额、实发工资等)，注: 其中实发工资=基本工资+补贴金额 + 奖励金额-扣除金额，要求职工数据保存到一个文件中。完成以下功能: (1)输入职工数据 (2)能够查询某位职工的相关数据 (3)能够对职工的各项信息进行修改 (4)能够统计出所有职工的平均工资 (5) 退出程序。

以下是用C语言编写的工资管理系统软件，包括职工数据的输入、查询、修改、统计和退出功能。

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

struct Employee {
    int id; // 职工号
    char name[20]; // 姓名
    float basic_salary; // 基本工资
    float subsidy; // 补贴金额
    float bonus; // 奖励金额
    float deduction; // 扣除金额
    float actual_salary; // 实发工资
};

// 声明函数
void input_employee_data(struct Employee *employee);
void output_employee_data(struct Employee employee);
void modify_employee_data(struct Employee *employee);
void calculate_average_salary(struct Employee *employees, int size);
int find_employee_by_id(struct Employee *employees, int size, int id);

int main() {
    struct Employee employees[100]; // 最多100个职工
    int employee_count = 0;
    int choice;

    // 从文件中读取职工数据
    FILE *file = fopen("employees.dat", "rb");
    if (file != NULL) {
        fread(&employee_count, sizeof(int), 1, file);
        fread(employees, sizeof(struct Employee), employee_count, file);
        fclose(file);
    }

    while (1) {
        printf("\n");
        printf("1. 输入职工数据\n");
        printf("2. 查询职工数据\n");
        printf("3. 修改职工数据\n");
        printf("4. 统计平均工资\n");
        printf("5. 退出程序\n");
        printf("请选择操作: ");
        scanf("%d", &choice);
        printf("\n");

        switch (choice) {
            case 1:
                input_employee_data(&employees[employee_count]);
                employee_count++;
                break;
            case 2: {
                int id;
                printf("请输入职工号: ");
                scanf("%d", &id);
                int index = find_employee_by_id(employees, employee_count, id);
                if (index == -1) {
                    printf("没有找到职工号为%d的职工\n", id);
                } else {
                    output_employee_data(employees[index]);
                }
                break;
            }
            case 3: {
                int id;
                printf("请输入职工号: ");
                scanf("%d", &id);
                int index = find_employee_by_id(employees, employee_count, id);
                if (index == -1) {
                    printf("没有找到职工号为%d的职工\n", id);
                } else {
                    modify_employee_data(&employees[index]);
                }
                break;
            }
            case 4:
                calculate_average_salary(employees, employee_count);
                break;
            case 5:
                // 保存职工数据到文件中
                file = fopen("employees.dat", "wb");
                if (file != NULL) {
                    fwrite(&employee_count, sizeof(int), 1, file);
                    fwrite(employees, sizeof(struct Employee), employee_count, file);
                    fclose(file);
                }
                exit(0);
                break;
            default:
                printf("无效的操作，请重新输入\n");
                break;
        }
    }

    return 0;
}

// 输入职工数据
void input_employee_data(struct Employee *employee) {
    printf("请输入职工号: ");
    scanf("%d", &employee->id);
    printf("请输入姓名: ");
    scanf("%s", employee->name);
    printf("请输入基本工资: ");
    scanf("%f", &employee->basic_salary);
    printf("请输入补贴金额: ");
    scanf("%f", &employee->subsidy);
    printf("请输入奖励金额: ");
    scanf("%f", &employee->bonus);
    printf("请输入扣除金额: ");
    scanf("%f", &employee->deduction);
    employee->actual_salary = employee->basic_salary + employee->subsidy + employee->bonus - employee->deduction;
}

// 输出职工数据
void output_employee_data(struct Employee employee) {
    printf("职工号: %d\n", employee.id);
    printf("姓名: %s\n", employee.name);
    printf("基本工资: %.2f\n", employee.basic_salary);
    printf("补贴金额: %.2f\n", employee.subsidy);
    printf("奖励金额: %.2f\n", employee.bonus);
    printf("扣除金额: %.2f\n", employee.deduction);
    printf("实发工资: %.2f\n", employee.actual_salary);
}

// 修改职工数据
void modify_employee_data(struct Employee *employee) {
    int choice;
    printf("1. 修改姓名\n");
    printf("2. 修改基本工资\n");
    printf("3. 修改补贴金额\n");
    printf("4. 修改奖励金额\n");
    printf("5. 修改扣除金额\n");
    printf("请选择要修改的项目: ");
    scanf("%d", &choice);
    switch (choice) {
        case 1:
            printf("请输入新的姓名: ");
            scanf("%s", employee->name);
            break;
        case 2:
            printf("请输入新的基本工资: ");
            scanf("%f", &employee->basic_salary);
            employee->actual_salary = employee->basic_salary + employee->subsidy + employee->bonus - employee->deduction;
            break;
        case 3:
            printf("请输入新的补贴金额: ");
            scanf("%f", &employee->subsidy);
            employee->actual_salary = employee->basic_salary + employee->subsidy + employee->bonus - employee->deduction;
            break;
        case 4:
            printf("请输入新的奖励金额: ");
            scanf("%f", &employee->bonus);
            employee->actual_salary = employee->basic_salary + employee->subsidy + employee->bonus - employee->deduction;
            break;
        case 5:
            printf("请输入新的扣除金额: ");
            scanf("%f", &employee->deduction);
            employee->actual_salary = employee->basic_salary + employee->subsidy + employee->bonus - employee->deduction;
            break;
        default:
            printf("无效的操作，请重新输入\n");
            break;
    }
}

// 统计平均工资
void calculate_average_salary(struct Employee *employees, int size) {
    float total_salary = 0;
    for (int i = 0; i < size; i++) {
        total_salary += employees[i].actual_salary;
    }
    float average_salary = total_salary / size;
    printf("所有职工的平均工资是: %.2f\n", average_salary);
}

// 根据职工号查找职工，返回索引，如果没找到则返回-1
int find_employee_by_id(struct Employee *employees, int size, int id) {
    for (int i = 0; i < size; i++) {
        if (employees[i].id == id) {
            return i;
        }
    }
    return -1;
}

职工数据会保存到文件`employees.dat`中，每次运行程序时会从文件中读取职工数据，程序退出时会将职工数据保存到文件中。每个职工的数据包括职工号、姓名、基本工资、补贴金额、奖励金额、扣除金额和实发工资。程序提供了输入职工数据、查询职工数据、修改职工数据、统计平均工资和退出程序等功能。