面试题：C语言结构体嵌套与动态内存管理

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

// 定义员工结构体
typedef struct Employee {
    char name[50];
    char position[50];
    double salary;
} Employee;

// 定义部门结构体
typedef struct Department {
    char name[50];
    Employee *employees;
    int employeeCount;
} Department;

// 创建部门
Department* createDepartment(const char *departmentName) {
    Department *department = (Department*)malloc(sizeof(Department));
    if (department == NULL) {
        perror("Memory allocation failed");
        return NULL;
    }
    strcpy(department->name, departmentName);
    department->employees = NULL;
    department->employeeCount = 0;
    return department;
}

// 向部门添加员工
void addEmployee(Department *department, const char *name, const char *position, double salary) {
    department->employees = (Employee*)realloc(department->employees, (department->employeeCount + 1) * sizeof(Employee));
    if (department->employees == NULL) {
        perror("Memory allocation failed");
        return;
    }
    strcpy(department->employees[department->employeeCount].name, name);
    strcpy(department->employees[department->employeeCount].position, position);
    department->employees[department->employeeCount].salary = salary;
    department->employeeCount++;
}

// 释放部门内存
void freeDepartment(Department *department) {
    free(department->employees);
    free(department);
}

int main() {
    int m = 3; // 假设添加3个员工
    Department *department = createDepartment("Engineering");
    if (department == NULL) {
        return 1;
    }

    addEmployee(department, "Alice", "Engineer", 5000.0);
    addEmployee(department, "Bob", "Senior Engineer", 7000.0);
    addEmployee(department, "Charlie", "Manager", 10000.0);

    // 打印部门信息
    printf("Department: %s\n", department->name);
    for (int i = 0; i < department->employeeCount; i++) {
        printf("Employee %d: Name - %s, Position - %s, Salary - %.2f\n", i + 1, department->employees[i].name, department->employees[i].position, department->employees[i].salary);
    }

    freeDepartment(department);
    return 0;
}

可能出现内存泄漏的情况及避免方法：

malloc或realloc失败：在调用malloc或realloc后，应立即检查返回值是否为NULL。如果为NULL，表示内存分配失败，此时不应继续使用未初始化的指针，否则可能导致未定义行为。在代码中，每次调用malloc和realloc后都进行了检查，若失败则打印错误信息并采取相应措施（如返回或结束程序）。
忘记释放内存：在使用完动态分配的内存后，必须调用free函数进行释放。在本代码中，定义了freeDepartment函数，先释放员工数组的内存，再释放部门结构体的内存，从而避免了内存泄漏。如果在程序结束前没有调用freeDepartment函数，那么分配给部门和员工的内存将不会被释放，导致内存泄漏。

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面试题：C语言结构体嵌套与动态内存管理

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可能出现内存泄漏的情况及避免方法：