一字符串,包含有n 个字符。编写一函数,将此字符串中从第m个字符开始的全部字符复制成为另一字符串

#include "stdio.h"
#include "string.h"
void fuzhi(char a[],char b[],int n);

void main()
{
int x;
char s1[30]="fengshuang";
char s2[30];
scanf("%d",&x);

fuzhi(s1,s2,x);
printf("%s\n",s2);
}

void fuzhi(char a[],char b[],int n)
{
char * p;
int i=0;
if( n > strlen(a) || n<=0 )
{
printf("输入超出字符串的大小");
}
p=&a[n];

while(*p)
{
b[i]=*p++;
i++;
}
b[i]='\0';
}