写一个建造者模式的c++代码实例

好的，这是一个简单的建造者模式的 C 代码实例：

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

/* Product */
typedef struct {
    char part1[20];
    char part2[20];
    char part3[20];
} Product;

/* Builder interface */
typedef struct {
    void (* build_part1)(Product *product);
    void (* build_part2)(Product *product);
    void (* build_part3)(Product *product);
} Builder;

/* Concrete builder */
typedef struct {
    Builder builder; /* Inherit from Builder interface */
    Product *product;
} ConcreteBuilder;

void build_part1(Product *product) {
    strcpy(product->part1, "Part 1");
}
void build_part2(Product *product) {
    strcpy(product->part2, "Part 2");
}
void build_part3(Product *product) {
    strcpy(product->part3, "Part 3");
}

void ConcreteBuilder_create(ConcreteBuilder *builder) {
    builder->builder.build_part1 = build_part1;
    builder->builder.build_part2 = build_part2;
    builder->builder.build_part3 = build_part3;
    builder->product = malloc(sizeof(Product));
}

void ConcreteBuilder_build(ConcreteBuilder *builder) {
    builder->builder.build_part1(builder->product);
    builder->builder.build_part2(builder->product);
    builder->builder.build_part3(builder->product);
}

Product *ConcreteBuilder_get_result(ConcreteBuilder *builder) {
    return builder->product;
}

/* Director */
typedef struct {
    void (* construct)(Builder *builder);
} Director;

void construct(Builder *builder) {
    builder->build_part1(builder);
    builder->build_part2(builder);
    builder->build_part3(builder);
}

void Director_construct(Director *director, Builder *builder) {
    director->construct(builder);
}

int main() {
    ConcreteBuilder builder;
    ConcreteBuilder_create(&builder);
    Director director = { construct };
    Director_construct(&director, &builder.builder);
    Product *product = ConcreteBuilder_get_result(&builder);

    printf("Product parts: %s, %s, %s\n", product->part1, product->part2, product->part3);

    free(product);
    return 0;
}

这里定义了一个 `Product` 结构体表示产品，具体包含三个部分 `part1`、`part2`、`part3`；同时定义了一个 `Builder` 接口以及一个 `ConcreteBuilder` 具体实现类。在 `ConcreteBuilder` 中实现了 `Builder` 中定义的三种构建方法，分别构建产品中的三个部分。`ConcreteBuilder` 将这三个构建方法包装起来，在调用 `ConcreteBuilder_build` 方法时，一次性将三个部分构建出来。`ConcreteBuilder_get_result` 方法最终返回构建的产品。

在 `Director` 结构体中，定义了一个 `construct` 方法，其接收一个 `Builder` 接口，使得构造产品的过程得以独立出来。在例子中，创建了一个 `ConcreteBuilder`，使用 `Director` 中的 `construct` 方法构建了一个 `Product`，再通过 `get_result` 方法获取构建好的产品，并打印出来。