C 反转字符串 "abcd" --> "dcba"

#include<stdio.h>

void test(char *p)
{
static char *ep = p;
char aa = *p;
if(*p != '\0')
test(p+1);
else
return;
*ep = aa;
ep++;
}

int main()
{
char a[] = "abcd";
test(a);
printf("%s\n",a);

return 0;
}