Programming Abstractions in C阅读笔记：p331-p337

《Programming Abstractions in C》学习第79天，p331-p337，总计7页。

一、技术总结

/*
 * File: stack.h
 * -------------
 * This interface defines an abstraction for stacks. In any
 * single application that uses this interface, the values in
 * the stack are constrained to a single type, although it
 * is easy to change that type by changing the definition of
 * stackElementT in this interface.
 */

#ifndef _stack_h
#define _stack_h

#include "genlib.h"

/*
 * Type: stackElementT
 * -------------------
 * The type stackElementT is used in this interface to indicate
 * the type of values that can be stored in the stack. Here the
 * stack is used to store values of type double, but that can
 * be changed by editing this definition line.
 */

typedef double stackElementT;

/*
 * Type: stackADT
 * --------------
 * The type stackADT represents the abstract typed used to store
 * the elements that have been pushed. Because stackADT is
 * defined only as a pointer to a concrete structure that is not
 * itself defined in the interface, clients have no access to
 * the underlying fields.
 */

typedef struct stackCDT *stackADT;

/*
 * Function: NewStack
 * Usage: stack = NewStack();
 * --------------------------
 * This function allocates and returns a new stack, which is
 * initially empty.
 */

stackADT NewStack(void);

/*
 * Function: FreeStack
 * Usage: FreeStack(stack);
 * ------------------------
 * This function free the storage associated with the stack.
 */

void FreeStack(stackADT stack);

/*
 * Function: Push
 * Usage: Push(stack, element);
 * ----------------------------
 * This function pushes the specified element onto the stack;
 */
void Push(stackADT stack, stackElementT element);


/*
 * Function: Pop
 * Usage: element = Pop(stack);
 * -----------------------------
 * This function pops the top element from the stack and returns
 * that value. The first value popped is always the last one
 * that was pushed. If the stack is empty when Pop is called,
 * the function calls Error with an appropriate message.
 */

stackElementT Pop(stackADT stack);


/*
 * Function: StackIsEmpty, StackIsFull
 * Usage: if (StackIsEmpty(stack)) ...
 *        if (StackIsFull(stack)) ...
 * ---------------------------------------
 * This function test whether the stack is empty or full.
 */

bool StackIsEmpty(stackADT stack);
bool StackIsFull(stackADT stack);

/*
 * Function: StackDepth
 * Usage: depth = StackDepth(stack);
 * ---------------------------------
 * This function returns the number of elements currently pushed
 * on the stack.
 */
int StackDepth(stackADT stack);


/*
 * Function: GetStackElement
 * Usage: element = GetStackElement(stack, index);
 * -----------------------------------------------
 * This function returns the element at the specified index in
 * the stack, where the top of the stack is defined as index 0.
 * For example, calling GetStackElement(stack, 0) returns the top
 * element on the stack without removing it. If the caller tries
 * to select an out-of-range element, GetStackElement calls Error.
 * Note: This function is not a fundamental stack operation and
 * is instead provided principally to facilitate debugging.
 */
stackElementT  GetStackElement(stackADT stack, int index);

#endif

二、英语总结

1.polymorphism是什么意思？

答：

(1)polymorphous > polymorph > polymorphism

(2)polymorphous: poly"many" + morphē “shape, form,”。adj. have various forms。

(3)polymorphism: capability of existing in different forms(多态性)。

p332, the ability to apply the same function to objects of different types called polymorhpism。

2.overhead用法总结

答：

(1)n. the regular and necessary costs(开销)。p332, In some cases, however, forcing the clients to use pointer as data values imposes an unacceptable level of overhead.

平时大多做副词用，也可以做名词。

3.compromise是什么意思？

答：com-(together) + promise，c/u. a joint promise to abide by an arbiter’s decision(妥协)。 abide by sth: to accept or obey an aggrement。

4.as far as sth is concerned是什么意思？

答：If we are discussing or thinking about a particular thing(就…而言)。

5.relinquish是什么意思？

答：vt. to give up sth such as responsibility or claim(放弃，舍弃)。p335, Thus, in addition to the function NewStack, you need a symmetric funciton FreeStack, that takes a buffer and relinquishes any dynamically allocated storage it contains。