字符串之_strncat

功能：将src的前n个字符添加到dest的后面

输入:dest,src,count

返回：ret

#include <iostream>
#include <assert.h>
using namespace std;
char * _strncat(char *dest,const char *src,int count)
{
	assert((dest != NULL)&&(src != NULL));
	char *ret = dest;
	while(*dest != '\0') dest++;
	while (count--)
	{
		if (!(*dest++ = *src++))
		{
			return ret;
		}

	}
	*dest = '\0';
	return ret;
}

int main()
{
	 char str1[20] = "abcdef";
	 char str2[20] = "hello world";
	cout << _strncat(str1,str2,3)<<endl;
	return 0;
};