【字符串】字符串拷贝和长度

#include <iostream>
#include <assert.h>
using namespace std;

//字符串长度
int strlen_bxy(const char *str)
{
	assert(str != NULL);
	int len = 0;
	while(*str++ != '\0')
	{
		++len;
	}
	return len;
}

//字符串拷贝
char *strcpy_bxy(char *to,const char *from)
{
	assert((to != NULL) && (from != NULL));
	char *result = to;
	while((*to++ = *from++) != '\0');
	return result;
}

//
char *strncpy_bxy(char *to,const char *from,size_t count)
{
	assert((to != NULL) && (from != NULL));
	char *result = to;
	while(count--)
	{
		if(*from != '\0')
		{
			*to++ = *from++;
		}
		else
		{
			*to++ = '\0';
		}
	}
	*to++ = '\0';
	return result;
}
void main()
{
	const char *str = "[email protected]";
	//测试strlen函数
	cout << strlen_bxy(str)<<endl;
	int length = strlen_bxy(str);
	char *copy = new char[length+1];
	strcpy_bxy(copy,str);
	cout << copy <<endl;

	char *ncopy = new char[7];
	strncpy_bxy(ncopy,str,6);
	cout << ncopy <<endl;
}