C++(OOP)异常

• 传统处理方法
• C++处理异常方法
  • try
  • catch
  • throw
  • 异常类型
    • 数字
    • 字符串
    • 类对象

#include 
#include 

using namespace std;

class BadSrcFile{
     };
class BadDestFile{
     };
class BadCopy{
     };

int my_cp(const char * src_file, const char * dest_file)
{
     
	FILE * in_file, *out_file;
	in_file = fopen(src_file, "rb");
	if(in_file == NULL)
	{
     
		return 1;
	}

	out_file = fopen(dest_file, "wb");
	if (out_file == NULL)
	{
     
		return 2;
	}

	char rec[256];
	size_t bytes_in, bytes_out;
	while(bytes_in = fread(rec, 1, 256, in_file))
	{
     
		bytes_out = fwrite(rec, 1, bytes_in, out_file);
		if (bytes_in != bytes_out)
		{
     
			return 3;
		}
	}
	fclose(in_file);
	fclose(out_file);

	return 0;
}

int my_cp2(const char * src_file, const char * dest_file)
{
     
	FILE * in_file, *out_file;
	in_file = fopen(src_file, "rb");
	if(in_file == NULL)
	{
     
		throw 1;  // throw就是抛出异常
	}

	out_file = fopen(dest_file, "wb");
	if (out_file == NULL)
	{
     
		throw 2;
	}

	char rec[256];
	size_t bytes_in, bytes_out;
	while(bytes_in = fread(rec, 1, 256, in_file))
	{
     
		bytes_out = fwrite(rec, 1, bytes_in, out_file);
		if (bytes_in != bytes_out)
		{
     
			throw 3;	
		}
	}
	fclose(in_file);
	fclose(out_file);

//	return 0;
}

int my_cp3(const char * src_file, const char * dest_file)
{
     
	FILE * in_file, *out_file;
	in_file = fopen(src_file, "rb");
	if(in_file == NULL)
	{
     
		throw "打开源文件时出错!";  // throw就是抛出异常
	}

	out_file = fopen(dest_file, "wb");
	if (out_file == NULL)
	{
     
		throw "打开目标文件时出错!";
	}

	char rec[256];
	size_t bytes_in, bytes_out;
	while(bytes_in = fread(rec, 1, 256, in_file))
	{
     
		bytes_out = fwrite(rec, 1, bytes_in, out_file);
		if (bytes_in != bytes_out)
		{
     
			throw "拷贝文件时出错!";	
		}
	}
	fclose(in_file);
	fclose(out_file);

//	return 0;
}

int my_cp4(const char * src_file, const char * dest_file)
{
     
	FILE * in_file, *out_file;
	in_file = fopen(src_file, "rb");
	if(in_file == NULL)
	{
     
		throw BadDestFile();
	}

	out_file = fopen(dest_file, "wb");
	if (out_file == NULL)
	{
     
		throw BadDestFile();
	}

	char rec[256];
	size_t bytes_in, bytes_out;
	while(bytes_in = fread(rec, 1, 256, in_file))
	{
     
		bytes_out = fwrite(rec, 1, bytes_in, out_file);
		if (bytes_in != bytes_out)
		{
     
			throw BadCopy();
		}
	}
	fclose(in_file);
	fclose(out_file);

//	return 0;
}
int main()
{
     
//	int result;
//	if(result = my_cp("1.txt", "2.txt")!= 0)
//	{
     
//		switch(result)
//		{
     
//			case 1:
//				printf("打开源文件时出错!\n");
//				break;
//			case 2:
//				printf("打开目标文件时出错!\n");
//				break;
//			case 3:
//				printf("拷贝文件时出错!\n");
//				break;
//			default:
//				printf("发送未知错误!\n");
//				break;
//		}
//	}

	try
	{
     

		my_cp2("1.txt", "2.txt");
		my_cp3("1.txt", "2.txt");
		my_cp4("11.txt", "2.txt");
	}
	catch(int e)
	{
     
		printf("发生异常:%d\n", e);	
	}
	catch(const char *e)
	{
     
		printf("%s\n", e);
	}
	catch(BadSrcFile e)
	{
     
		printf("发送异常：打开源文件时出错!\n");
	}
	catch(BadDestFile e)
	{
     
		printf("发送异常：打开目标文件时出错!\n");
	}
	catch(BadSrcFile e)
	{
     
		printf("发送异常：拷贝文件出错!\n");
	}
	catch(...)
	{
     
		printf("其他异常!\n");
	}

	printf("Ok!\n");	
	return 0;
}