C language implementation of strncpy

1.strncpy Introduce

strncpy --- String copy --- Copy num Characters

char* strncpy ( char* destination, const char* source, size_t num )

Copy num Characters from the source string to the target space ;

If the source string length is less than num, After copying the source string , Add... After the target ’\0‘, until num individual .

2.strncpy Realization

#include<stdio.h>
#include<assert.h>
#include<stdlib.h>
#include<string.h>


char* my_strncpy(char* destination, const char* source,unsigned int num)
{
	assert(destination && source);
	char* ret = destination;
	while (num&&(*destination++ = *source++))
	{
		num--;
	}
	if (num != 0)
	{
		while (num)
		{
			*destination++ = '\0';
			num--;
		}
	}
	return ret;
}

int main()
{
	char arr1[30] = "abcdef";
	char arr2[] = "bit";
	my_strncpy(arr1, arr2,6);
	printf("%s",arr1);
	return 0;
}