回文判断

//
#include"stdio.h"
#include"stdlib.h"
typedef char ElemType;
typedef struct stnode
{
  ElemType data;
  struct stnode* next;
}StNode, * LinkStack;
int huiwen(char str[])
{
  int i = 0;
  char ch;
  StNode* sl = NULL, * p;
  while ((ch = str[i++]) != '\0')
  {
    p = (StNode*)malloc(sizeof(StNode));//给内存
    p->data = ch;
    p->next = sl;
    sl = p;
  }
  i = 0;
  while (sl != NULL)
  {
    p = sl;
    ch = p->data;
    sl = sl->next;
    free(p);//释放内存
    if (ch != str[i++])
      return 0;
  }
  return 1;
}
void main()
{
  char string[30];//最长为30
  int hw;
  printf("请输入字符串:");
  gets_s(string);
  hw = huiwen(string);
  if (hw) printf("字符串是回文.");
  else printf("字符串不是回文");
}