スタックの方法はポーランドのサフィックス式に逆です.

#define  _CRT_SECURE_NO_WARNINGS
#include
#include
#include

#define STACK_INIT_SIZE 20
#define STACKINCREMENT  10
#define MAXBUFFER       10

typedef   double    ElemType;

typedef struct
{
	ElemType *base;
	ElemType *top;
	int stackSize;
}sqStack;

void InitStack(sqStack *s)
{
	s->base =(ElemType*)malloc(STACK_INIT_SIZE*sizeof(ElemType));
	if(!s->base)
		exit(0);
	s->top = s->base;

	s->stackSize = STACK_INIT_SIZE;
}

int Push(sqStack *s,ElemType e)
{
	if(s->top-s->base >= s->stackSize)
	{
		s->base=(ElemType*)realloc(s->base,(s->stackSize+STACKINCREMENT)*sizeof(ElemType));
		s->top=s->base+s->stackSize;
		s->stackSize=s->stackSize +STACKINCREMENT;
	}
	*(s->top)=e;
	s->top++;
	return 1;
}
int Pop(sqStack *s,ElemType *e)
{
	if(s->top==s->base)
		return 0;
	*e=*--(s->top);
	return 1;
}
int StackLen(sqStack s)
{
	return (s.top-s.base);
}


int main()
{
	sqStack s;
	char c;
	int i=0;;
	double d,e;
	char str[MAXBUFFER];
	InitStack(&s);
	printf("               ，             ， #    
");
	scanf("%c",&c);
	while(c!='#')
	{
		while(isdigit(c)||c=='.')
		{
			str[i++]=c;
			str[i]='\0';
			if(i>=10)
			{
				printf("  ：         ！
");
				return -1;
			}
			scanf("%c",&c);
			if(c==' ')
			{
				d=atof(str);
				Push(&s,d);
				i=0;
				break;
			}

		}
		switch (c)
		{
		case '+':
			Pop(&s,&e);
			Pop(&s,&d);
			Push(&s,d+e);
			break;
		case '-':
			Pop(&s,&e);
			Pop(&s,&d);
			Push(&s,d-e);
			break;
		case '*':
			Pop(&s,&e);
			Pop(&s,&d);
			Push(&s,d*e);
			break;
		case '/':
			Pop(&s,&e);
			Pop(&s,&d);
		//	Push(&s,d/e);
			if(e!=0)
			{
				Push(&s,d/e);
			}
			else
			{
				printf("
  ：   0！
");
			}
			break;

		}
		scanf("%c",&c);
	}
	Pop(&s,&d);
	printf("        ：%f
",d);
	system("pause");
	return 0;
}