void main(void){

  char * pahcr=NULL;

  pchar=(char *)malloc(1);
  cout<<"申请的地址为:"<<pchar<<endl;
  cout<<"请输入一个字符"<<endl;
  scanf("%c",pchar);
  cout<<"你输入的字符为"<<endl;
  printf("%c\n",*pchar);
  free(pchar);//执行该语句后发生错误为什么
  pchar=NULL;
  cout<<"释放掉指针后地址为"<<pchar<<endl;

}