顺序栈的表示和实现

表示

typedef struct
{
    data_t    *data;    /* storage of the stack, 
             * in array, dynamic allocated 
             */
    int    top;    /* current top of the stack, the value of 
             * top is the index of the data array.
             * note the type of stack we create here
             * is "full-stack", which means the top always
             * points to the location in which the last 
             * item was stored. A push will first 
             * increment the stack pointer, then store
             * the value. Another stack type is called
             * "empty-stack": of which the top points to 
             * the location in which the next item will be 
             * stored. A push will first store the value, 
             * and then increment the stack pointer. 
             */
    int    max_depth; /* max depth of stack, initialized when the 
                * stack is created, used to limit top
                * not exceed the max depth 
                */
} sqstack_t;

实现

//创建
sqstack_t *CreateEmptySqstack(int max_depth)
{
    sqstack_t *stack;
    if (max_depth == 0)
        return NULL;
        
    stack = (sqstack_t *)malloc(sizeof(sqstack_t));
    if (stack == NULL)
        return NULL;
        
    stack->data = (data_t *)malloc(sizeof(data_t) * max_depth);
    if (stack->data == NULL) {
        free(stack);
        return NULL;
    }
    
    stack->top = -1;
    stack->max_depth = max_depth;
    return stack;
}
//清空
int ClearSqstack(sqstack_t *stack)
{
    if (NULL != stack) {
        stack->top = -1;
        return 0;
    } else {
        return -1;
    }

}
//销毁
int DestroySqstack(sqstack_t *stack)
{
    if (NULL != stack) {
        if (stack->data != NULL)
            free(stack->data);
        free(stack);
        return 0;
    } else {
        return -1;
    }
}
//是否为空
int EmptySqstack(sqstack_t *stack)
{
    if (NULL != stack) {
        return (-1 == stack->top ? 1 : 0);
    } else {
        return -1;
    }
}
//是否为满
int FullSqstack(sqstack_t *stack)
{
    if (NULL != stack) {
        return ((stack->max_depth - 1) == stack->top ? 1 : 0 );
    } else {
        return -1;
    }
}
//压栈
int PushStack(sqstack_t *stack, data_t x)
{
    if (NULL == stack) return -1;
    if (FullSqstack(stack)) return -1;
        
    stack->top++;
    stack->data[stack->top] = x;
    return 0;
}
//出栈
int PopStack(sqstack_t *stack, data_t *x)
{
    if (NULL == stack) return -1;
    if (EmptySqstack(stack)) return -1;
    if (NULL == x) return -1;
    
    *x = stack->data[stack->top];
    stack->top--;
    return 0;
}
//获取栈顶
int GetTop(sqstack_t *stack, data_t *x)
{
    if (NULL == stack) return -1;
    if (NULL == x) return -1;
    if(EmptySqstack) return -1;
        
    *x = stack->data[stack->top];
    return 0;
}

测试代码

int Push_Pop(sqstack_t *stack, data_t x);

/*
 * iterate through the stack, from the base to the top 
 * and print out info of each element
 */
void iterate_stack(sqstack_t *stack)
{
    int i;
    
    if (!stack) return;

    printf("stack = base{");
    
    if (stack->data) { /* just for protection */
        for (i = -1; i < stack->top;) {
            printf("%d,", stack->data[++i]);
        }    
    }
    
    if (1 == EmptySqstack(stack))
        printf("}top
");
    else
        printf("}top
");
}

int main(int argc, char *argv[])
{
    sqstack_t *stack;
    int max_depth;

    if (argc < 2) {
        printf("Usage: %s <max_depth>
", argv[0]);
        return -1;
    }

    max_depth = atoi(argv[1]);
    
    stack = CreateEmptySqstack(max_depth);

    if (!stack) {
        printf("CreateEmptySqstack error
");
        return -1;
    }

    Push_Pop(stack, 1);

    DestroySqstack(stack);
    
    return 0;
}

int Push_Pop(sqstack_t *stack, data_t x)
{
    data_t data_pop;
    
    if (FullSqstack(stack)) {
        printf("----- reach the max depth of the stack!
");
        return 0;
    } else {
        printf("Push %d
", x);
        PushStack(stack, x++);
        iterate_stack(stack);

        Push_Pop(stack, x);

        PopStack(stack, &data_pop);
        printf("Pop %d
", data_pop);
        iterate_stack(stack);

        return -1;
    }
}

结果

Push 1
stack = base{1}top
Push 2
stack = base{1,2}top
Push 3
stack = base{1,2,3}top
Push 4
stack = base{1,2,3,4}top
Push 5
stack = base{1,2,3,4,5}top
Push 6
stack = base{1,2,3,4,5,6}top
Push 7
stack = base{1,2,3,4,5,6,7}top
Push 8
stack = base{1,2,3,4,5,6,7,8}top
----- reach the max depth of the stack!
Pop 8
stack = base{1,2,3,4,5,6,7}top
Pop 7
stack = base{1,2,3,4,5,6}top
Pop 6
stack = base{1,2,3,4,5}top
Pop 5
stack = base{1,2,3,4}top
Pop 4
stack = base{1,2,3}top
Pop 3
stack = base{1,2}top
Pop 2
stack = base{1}top
Pop 1
stack = base{}top