异常处理的正规方法

#include<iostream>
using namespace std;

int str_cpy(char * to, char *from)
{
	if (from == NULL)
	{
		return 1;
	}
	if (to == NULL)
	{
		return 2;
	}
	if (*from == ‘a‘)
	{
		return 3;
	}
	while (*from != ‘\0‘)
	{
		*to = *from;
		to++;
		from++;
	}
	*to = ‘\0‘;
	return 0;//这句话只管重要，如果不返回零的话，下面的case中就会执行default的命令行。
}
int main()
{
	int a = 0;
	char buf1[28] = "dfewgs";
	//char *buf2 = new char[strlen(buf1)+1];
	char buf2[128] = { 0 };
	a = str_cpy(buf2, buf1);
	if(a != 0)
	{
		switch (a)
		{
		case 1:
			break;
		case 2:
			break;
		case 3:
			cout << "case3\n";
			break;
		default:
			cout << "default\n";
			break;
		}
	}

	cout << buf2 << endl;
	system("pause");
}