스택 구조(C 언어)

# include 
# include 
# include 

//    
typedef struct Node
{
    int data;               //     
    struct Node * pNext;    //     ，     NODE    
}NODE, * PNODE;

//   
typedef struct Stack
{
    PNODE pTop;         //     
    PNODE pBottom;      //     
}STACK, * PSTACK;

//     
void init(PSTACK pS);
//  
void push(PSTACK pS,int val);
//       
bool isEmpty(PSTACK pS);
//  
bool pop(PSTACK pS,int * val);
//    
void traverse(PSTACK pS);

int main(void)
{   
    STACK S;
    int val;

    init(&S);
    push(&S,1);
    push(&S,2);
    push(&S,3);
    push(&S,4);

    traverse(&S);

    if(pop(&S,&val)){
        printf("      %d 
", val);
    }else{
        printf("       
");
    }

    traverse(&S);

    return 0;
}

void init(PSTACK pS)        //      ，        
{
    pS->pTop = (PNODE)malloc(sizeof(NODE));
    if(pS->pTop == NULL){
        printf("        ");
        exit(-1);
    }else{
        pS->pBottom = pS->pTop;
        pS->pTop->pNext = NULL;  //     ，           
    }
}

void push(PSTACK pS,int val)
{
    //         
    PNODE pNew = (PNODE)malloc(sizeof(NODE));
    if(pNew == NULL){
        printf("        ");
        exit(-1);
    }else{

        pNew->data = val;        //       
        pNew->pNext = pS->pTop;  //     pTop;
        pS->pTop = pNew;         //          pTop 
    }
}

void traverse(PSTACK pS)
{   
    PNODE p = pS->pTop;
    while(p != pS->pBottom)     //       
    {   
        printf("%d ",p->data);
        p = p->pNext;
    }
    printf("
");
}

bool isEmpty(PSTACK pS)
{
    if(pS->pTop == pS->pBottom){
        return true;
    }else{
        return false;
    }
}

//    
bool pop(PSTACK pS,int * val)
{
    if(isEmpty(pS)){
        return false;
    }else{
        PNODE r = pS->pTop;     //          
        * val = r->data;        //    
        pS->pTop = r->pNext;    //     top
        free(r);
        r = NULL;
        
        return true;
    }
}