写一个库存管理系统的代码 C语言

好的，下面是一个简单的库存管理系统的 C 代码示例：

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

typedef struct {
    int id;
    char name[50];
    float price;
    int quantity;
} Product;

typedef struct {
    Product *products;
    int size;
} Inventory;

void add_product(Inventory *inventory, int id, char *name, float price, int quantity) {
    // Allocate memory for new product
    Product *new_product = (Product *) malloc(sizeof(Product));

    // Set the attributes of the new product
    new_product->id = id;
    strcpy(new_product->name, name);
    new_product->price = price;
    new_product->quantity = quantity;

    // Add the new product to the inventory
    inventory->products = (Product *) realloc(inventory->products, (inventory->size + 1) * sizeof(Product));
    inventory->products[inventory->size] = *new_product;
    inventory->size++;

    // Free the memory used by the new product
    free(new_product);
}

int remove_product(Inventory *inventory, int id) {
    int i, j;
    for (i = 0; i < inventory->size; i++) {
        if (inventory->products[i].id == id) {
            // Shift all products after the removed product one index to the left
            for (j = i; j < inventory->size - 1; j++) {
                inventory->products[j] = inventory->products[j + 1];
            }

            // Resize the inventory to remove the last product
            inventory->size--;
            inventory->products = (Product *) realloc(inventory->products, inventory->size * sizeof(Product));

            return 1;
        }
    }
    return 0;
}

int update_product_quantity(Inventory *inventory, int id, int quantity) {
    int i;
    for (i = 0; i < inventory->size; i++) {
        if (inventory->products[i].id == id) {
            inventory->products[i].quantity = quantity;
            return 1;
        }
    }
    return 0;
}

Product *get_product(Inventory *inventory, int id) {
    int i;
    for (i = 0; i < inventory->size; i++) {
        if (inventory->products[i].id == id) {
            return &inventory->products[i];
        }
    }
    return NULL;
}

void display_inventory(Inventory *inventory) {
    int i;
    printf("ID\tName\tPrice\tQuantity\n");
    for (i = 0; i < inventory->size; i++) {
        printf("%d\t%s\t%.2f\t%d\n", inventory->products[i].id, inventory->products[i].name, inventory->products[i].price, inventory->products[i].quantity);
    }
}

int main() {
    Inventory inventory = { NULL, 0 };

    // Add some products to the inventory
    add_product(&inventory, 1, "Apple", 1.99, 100);
    add_product(&inventory, 2, "Banana", 0.99, 50);

    // Display the inventory
    display_inventory(&inventory);

    // Update the quantity of the first product and remove the second product
    update_product_quantity(&inventory, 1, 50);
    remove_product(&inventory, 2);

    // Display the inventory again
    display_inventory(&inventory);

    // Free the memory used by the inventory
    free(inventory.products);

    return 0;
}

这个系统包含了两个结构体，一个是 `Product` 结构体用于表示单个产品，另一个是 `Inventory` 结构体用于管理产品库存。

`Inventory` 结构体包含了添加、删除、更新和获取产品的函数。在这个示例中，我们创建了一个 `Inventory` 实例，并向里面添加了两个产品，并展示了整个库存。接着我们更新了第一个产品的库存数量，删除了第二个产品，再次展示了整个库存。

这个示例中使用了动态内存分配来管理产品和库存的数据结构，使用 `malloc()` 和 `realloc()` 函数来分配和重新分配内存，使用 `free()` 函数来释放内存。