用函数实现几个经典代码

#include<stdio.h>
#include<math.h>
void fun(int x)
{
int i;
if(x<=2)
printf("the number is prime\n");
else
{
for(i=2;i<sqrt(x);i+=2)
{
if(x%i==0)
break;
}
if(i<sqrt(x))
printf("the number is not prime\n");
else
printf("the number is prime\n");
}
}
int main()
{
int num;
printf("please input a number:\n");
scanf("%d",&num);
fun(num);
return 0;
}

#include<stdio.h>
void fun(int x)
{
if((x%4==0)&&(x%100!=0)||(x%400)==0)
printf("%d年是闰年\n",x);
else
printf("%d年不是闰年\n",x);
}
int main()
{
int year;
printf("please input year:\n");
scanf("%d",&year);
fun(year);
return 0;
}

#include<stdio.h>
void init(int a1[],int len1)
{
int j;
int a2[10]={0,1,2,3,4,5,6,7,8,9};
for(j=0;j<len1;j++)
{
a1[j]=a2[j];
printf("%d ",a1[j]);
}
}
void reverse(int a2[], int len2)
{
int k;
int a3[10]={0};
for(k=0;k<len2;k++)
{
a3[k]=a2[len2-1-k];
printf("%d ",a3[k]);
}
}
void empty(int a3[],int len3)
{
int h;
int a4[10]={0};
for(h=0;h<len3;h++)
{
a3[h]=a4[h];
printf("%d ",a3[h]);
}
}
int main()
{
int i;
int a[10]={0};
int len=10;
init(a,len);
printf("\n");
reverse(a,len);
printf("\n");
empty(a,len);
printf("\n");
}