一个好的C++模板程序

来自：使用IDA分析高级数据结构

#include <stdio.h> 
#include <malloc.h> 

// our structures 
// ============== 
// information about our customers 
struct customer_t { // a typical structure 
	long id; 
	char name[32]; 
	char sex; // 'm'ale - 'f'emale 
}; 

// we sell books 
struct book_t { 
	char title[128]; // an ASCII string 
}; 

// and we sell computer softwares 
struct software_info_t { // a structure containing various bitfields 
	unsigned int plateform : 2; // 2 bits reserved for the plateform - 
	// plateforms can be combined (0x03)
#define PC 0x1 // 0x01 
#define MAC 0x2 // 0x02 
	unsigned int os : 3; // 3 bits reserved for the OS - 
	// OS can be combined (0x1C) 
#define WINDOWS 0x1 // 0x04 
#define DOS 0x2 // 0x08 
#define OS_X 0x4 // 0x10 
	unsigned int category : 2; // 2 bits reserved for the category - 
	// categories can't be combined (0x60) 
#define DISASSEMBLY 0x1 // 0x20 
#define RECOVERY 0x2 // 0x40 
#define CRYPTOGRAPHY 0x3 // 0x60 
}; 

struct software_t { 
	software_info_t info; 
	char name[32]; 
}; 

struct softwares_t { 
	int iNum;
	software_t softs[];
};

// generic products we're selling 
enum product_category_t { // an enumerated type 
	BOOK, 
	SOFTWARE, 
	HARDWARE // we actually don't sell hardware 
}; 

union product_u { // an union to contain product information 
	// depending on its category 
	book_t book; 
	software_t software; 
	// struct hardware_t hardware; // we actually don't sell hardware 
}; 

struct product_t { // a structure containing another structure 
	long id; 
	product_category_t category; 
	product_u p; 
}; 

// our data 
// ======== 
// our customers 
customer_t customers[] = { // an initialized array to memorize our customers 
	{ 1, "Peter", 'm' }, 
	{ 2, "John", 'm' }, 
	{ 3, "Mary", 'f' }, 
	{ 0 } 
}; 

// our products 
book_t ida_book = { "IDA QuickStart Guide" }; 
softwares_t softwares = // an initialized variable length structure 
{ 
	3, 
	{ 
		{ { PC, WINDOWS|DOS, DISASSEMBLY }, "IDA Pro" }, 
		{ { PC|MAC, WINDOWS|OS_X, RECOVERY }, "PhotoRescue" }, 
		{ { PC, WINDOWS, CRYPTOGRAPHY }, "aCrypt" } 
	} 
}; 

#define PRODUCTS_COUNT 4 
// our functions 
// ============= 
// check software information 
int check_software(software_info_t software_info) 
{ 
	bool valid = true; 
	if (software_info.plateform & PC) 
	{ 
		if (! (software_info.plateform & MAC) && (software_info.os & OS_X)) 
			valid = false; // OS-X isn't yet available on PC ;) 
	} 
	else if (software_info.plateform & MAC) 
	{ 
		if (! (software_info.plateform & PC) && ((software_info.os & WINDOWS) || 
			(software_info.os & DOS))) 
			valid = false; // Windows & DOS aren't available on Mac... 
	} 
	else 
		valid = false; 
	return valid; 
} 

// check product category 
int check_product(product_category_t product_category) 
{ 
	bool valid = true; 
	if (product_category == HARDWARE) 
	{ 
		valid = false; 
		printf("We don't sell hardware for the moment...\n"); 
	} 
	return valid; 
} 

// print customer information 
void print_customer(customer_t *customer) 
{ 
	printf("CUSTOMER %04X: %s (%c)\n", customer->id, 
		customer->name, 
		customer->sex); 
} 

// print book information 
void print_book(book_t *book) 
{ 
	printf("BOOK: %s\n", book->title); 
} 

// print software information 
void print_software(software_t *software) 
{ 
	printf("SOFTWARE: %s:", software->name); 
	// plateform 
	// we use 'if', as plateforms can be combined 
	if (software->info.plateform & PC) 
		printf(" PC"); 
	if (software->info.plateform & MAC) 
		printf(" MAC"); 
	printf(";"); 
	// OS 
	// we use 'if', as os can be combined 
	if (software->info.os & WINDOWS) 
		printf(" WINDOWS"); 
	if (software->info.os & DOS) 
		printf(" DOS"); 
	if (software->info.os & OS_X) 
		printf(" OS-X"); 
	printf(";"); 
	// category 
	// we use 'switch', as categories can't be combined 
	switch(software->info.category) 
	{ 
	case DISASSEMBLY: 
		printf(" DISASSEMBLY"); 
		break; 
	case RECOVERY: 
		printf(" RECOVERY"); 
		break; 
	case CRYPTOGRAPHY: 
		printf(" CRYPTOGRAPHY"); 
		break; 
	} 
	printf("\n"); 
} 

// print product information 
bool print_product(product_t *product) 
{ 
	if (! check_product(product->category)) 
		return false; 
	printf("PRODUCT %04X: ", product->id); 
	switch(product->category) { 
	case BOOK: 
		print_book(&product->p.book); 
		break; 
	case SOFTWARE: 
		print_software(&product->p.software); 
		break; 
	} 
	return true; 
} 

// our main program 
// ================ 
void main() 
{ 
	// print customers listing 
	printf("CUSTOMERS:\n"); 
	customer_t *customer = customers; 
	while (customer->id != 0) 
	{ 
		print_customer(customer); 
		customer++; 
	} 
	// allocate a small array to store our products in memory 
	product_t *products = (product_t*) malloc(PRODUCTS_COUNT * sizeof(product_t)); 
	// insert our products 
	products[0].id = 1; 
	products[0].category = BOOK; 
	products[0].p.book = ida_book; 
	products[1].id = 2; 
	products[1].category = SOFTWARE; 
	products[1].p.software = softwares.softs[0]; // we insert softwares from our 
	// variable length structure 
	products[2].id = 3; 
	products[2].category = SOFTWARE; 
	products[2].p.software = softwares.softs[1]; 
	products[3].id = 4; 
	products[3].category = SOFTWARE; 
	products[3].p.software = softwares.softs[2]; 
	// verify and print each product 
	printf("\nPRODUCTS:\n"); 
	for (int i = 0; i < PRODUCTS_COUNT; i++) 
	{ 
		// check validity of the product category 
		if (! check_product(products[i].category)) 
		{ 
			printf("Invalid product !!!\n"); 
			break; 
		} 
		// check validity of softwares 
		if (products[i].category == SOFTWARE) 
		{ 
			if (! check_software(products[i].p.software.info)) 
			{ 
				printf("Invalid software !!!\n"); 
				break; 
			} 
		} 
		// and print the product 
		print_product(&products[i]); 
	} 
	free(products); 
}