一江春水向東流

/****************a simple stack**********************************/

#include <stdio.h>

#define STACK_INIT_SIZE 100
#define STACKINCREMENT? 10
typedef int bool;
#define TRUE?? 1
#define FALSE? 0
typedef struct
{
?char *base;
?char *top;
?int stacksize;
}sqStack;

//=======================function protoType=============================
bool InitStack(sqStack *stk);
bool DestroyStack(sqStack *stk);
bool ClearStack(sqStack *stk);
bool StackEmpty(sqStack stk);
int? StackLength(sqStack stk);
bool GetTop(sqStack stk, char *item);
bool Push(sqStack *s, char item);
bool Pop(sqStack *s, char *item);

bool InitStack(sqStack *stk)
{
?stk->base = (char *)malloc(STACK_INIT_SIZE * sizeof(char));
?if (!stk->base)
?return FALSE;
?stk->top = stk->base;
?stk->stacksize = STACK_INIT_SIZE;
?return TRUE;
}

bool GetTop(sqStack stk, char *item)
{
?if (stk.top == stk.base)
?return FALSE;
?item = (stk.top-1);
?return TRUE;
}

bool Push(sqStack *stk, char item)
{
?if (stk->top - stk->base >= stk->stacksize)
?{
??printf("allocate New Mem\n");
??stk->base = (char *)realloc(stk->base, (stk->stacksize + STACKINCREMENT)* sizeof(char));
??if (!stk->base)
??return FALSE;
??stk->top = stk->base + stk->stacksize;
??stk->stacksize += STACKINCREMENT;
?}
?*stk->top = item;
?stk->top++;
?return TRUE;
}

bool Pop(sqStack *stk, char* item)
{
?if (stk->top == stk->base)
?return FALSE;
?stk->top--;
?*item = *(stk->top);
?return TRUE;
}

bool StackEmpty(sqStack stk)
{
?if (stk.top == stk.base)
?return TRUE;
?else
?return FALSE;
}

bool ClearStack(sqStack *stk)
{
?stk->top = stk->base;
?memset(stk->base, 0, sizeof(char));
?if (stk->top)
?return TRUE;
?else
?return FALSE;
}
bool DestroyStack(sqStack *stk)
{
?free(stk->base);
?printf("free memery\n");
?return TRUE;
}????

int main(int argc, char** argv)
{
?sqStack stk;
?char ch;
?InitStack(&stk);
?ch = getchar();
?while(ch != EOF)
?{
??while(ch != EOF && ch != '\n')
??{
???switch (ch)
???{
????? case '#':
????Pop(&stk, &ch);
????break;
????? case '@':
????? ?ClearStack(&stk);
????? ?break;
????? case 'q':???????
??????? DestroyStack(&stk);
??????? exit(1);
??????? break;???????
????? default:
?????? Push(&stk, ch);
???}
???ch = getchar();
??}
??ClearStack(&stk);
??if (ch != EOF)
??ch = getchar();
?}
?DestroyStack(&stk);?
?return 1;
}

特別要注意的是堆棧的中操作棧頂的值，在就是對內存的操作