C語言程式設計之線性結構兩種常見的應用之:棧
先看下面的一個例子:
//////////////////////////////////////////////////
//一個示例說明記憶體在棧和堆中的分配
#include
#include
void f(int k)
{
int t;
double *p = (double *)malloc(100);
}
int main(void)
{
int i = 10;
int *q = (int *)malloc(10);
}
在棧中分配的記憶體,凡是靜態分配的都是在棧中分配
在堆中分配的記憶體,凡是動態分配的都是在堆中分配
什麼是棧?一種可以實現“先進後出“的儲存結構
分類:
靜態棧:以陣列為基本核心
動態棧:以連結串列為基本核心
演算法:
出棧push
入棧(壓棧)pop
應用:
1、函式呼叫。
2、中斷。
3、表示式求值。
4、記憶體分配。
5、緩衝處理
//一個示例:
#include
#include
#include
typedef struct Node{
int data;
struct Node * pNext;
}NODE,* PNODE;
typedef struct Stack{
PNODE pTop;//永遠指向棧頂元素
PNODE pBottom;//永遠指向棧底的下一個沒有實際意義的元素,類似連結串列的頭節點
}STACK,* PSTACK;
void init(PSTACK pS);//初始化
void push(PSTACK pS,int val);
void traverse(PSTACK pS);
bool pop(PSTACK pS,int * val);
bool is_empty(PSTACK pS);
void clear(PSTACK pS);
int main(void)
{
STACK s;
int popVal;
init(&s);//棧的初始化
push(&s,1);
push(&s,3);
push(&s,5);
push(&s,7);
traverse(&s);
if(pop(&s,&popVal))
{
printf(“pop stack is success!the pop value is %d\n”,popVal);
}
else
{
printf(“pop stack is failed!\n”);
}
traverse(&s);
if(pop(&s,&popVal))
{
printf(“pop stack is success!the pop value is %d\n”,popVal);
}
else
{
printf(“pop stack is failed!\n”);
}
traverse(&s);
if(pop(&s,&popVal))
{
printf(“pop stack is success!the pop value is %d\n”,popVal);
}
else
{
printf(“pop stack is failed!\n”);
}
traverse(&s);
if(pop(&s,&popVal))
{
printf(“pop stack is success!the pop value is %d\n”,popVal);
}
else
{
printf(“pop stack is failed!\n”);
}
traverse(&s);
if(pop(&s,&popVal))
{
printf(“pop stack is success!the pop value is %d\n”,popVal);
}
else
{
printf(“pop stack is failed!\n”);
}
traverse(&s);
push(&s,2);
push(&s,4);
push(&s,6);
push(&s,8);
traverse(&s);
clear(&s);
if(pop(&s,&popVal))
{
printf(“pop stack is success!the pop value is %d\n”,popVal);
}
// traverse(&s);
return 0;
}
void init(PSTACK pS)
{
PNODE pHead;
pHead = (PNODE)malloc(sizeof(NODE));
if(NULL == pHead)
{
printf(“分配記憶體失敗!”);
exit(-1);
}
pS->pTop = pHead;
pS->pBottom = pHead;
pS->pTop->pNext = NULL;
}
/****************************************************************************************************************************
psuh()函式說明:假設已經初始化了一個棧pTop忽和pBottom都指向了一個頭節點pHead,pHead->pNext = NULL,
這時執行第一次壓棧push操作,line1建立了一個節點pNew,line2給節點賦值,line3將pTop指向pNew,
注意:此時pTop是指向頭節點pHead的。line4將pTop指向pNew。
經過上述4步,壓入了第一個棧節點。壓入第二個棧節點以此類推!
關鍵是line3和line4!!!
***************************************************************************************************************************/
void push(PSTACK pS,int val)
{
PNODE pNew = (PNODE)malloc(sizeof(NODE));//line1
pNew->data = val;//line2
pNew->pNext = pS->pTop;//不能是pBottom,line3
pS->pTop = pNew;//line4
}
void traverse(PSTACK pS)
{
PNODE p = pS->pTop;
while(pS->pBottom != p)
{
printf(“%d ”,p->data);
p = p->pNext;
}
printf(“\n”);
}
bool is_empty(PSTACK pS)
{
if(pS->pBottom == pS->pTop)
return true;
else
return false;
}
bool pop(PSTACK pS,int * val)
{
if(is_empty(pS))
{
printf(“the stack is empty!\n”);
return false;
}
PNODE p = pS->pTop;
* val = p->data;
pS->pTop = p->pNext;
free(p);
p = NULL;
return true;
}
void clear(PSTACK pS)
{
if(is_empty(pS))
return;
else
{
PNODE p = pS->pTop;
PNODE q = NULL;
while(pS->pBottom != p)
{
q = p->pNext;
free(p);
p = q;
}
pS->pTop = pS->pBottom;
}
}
~~~~~~~~~~~~~~~end~~~~~~~~~~~~~~~~~~~