模拟实现strncpy

#include<stdio.h>

#include<assert.h>

#include<string.h>

char* my_strncpy(char* dest,const char* src,size_t len)

{

	char* ret = dest;

  int offset = 0;

	assert(dest != NULL);

	assert(src != NULL);

	if(strlen(src) < len)

	{

	  offset = len - strlen(src);

		len = strlen(src);

	}

	while(len)

	{

	  *dest++ = *src++;

		len--;

	}

	while(offset)

	{

	  *dest++ = '\0';

		offset--;

	}

	return ret;

}

int main()

{

	char arr1[20] = "abcdef";

	char arr2[] = "xxxx";

	my_strncpy(arr1,arr2,3);

	printf("%s\n",arr1);

  return 0;

}