C++ Programming: A Step-by-Step Guide to Learn, in an Easy Way, the Fundamentals of C++ Programming Language by Aronowitz Alexander

Author:Aronowitz, Alexander [Aronowitz, Alexander]
Language: eng
Format: azw3, epub
Published: 2020-09-14T16:00:00+00:00

void f2 (T a) // variant with control

{

T v [200];

CheckedPtrToT p (& v [0], v, 200);

p--;

* p = a; // dynamic error:

// `p 'out of bounds of array

++ p;

* p = a; // fine

}

Increment and decrement are the only operations in C ++ that can be used as postfix and prefix operations. Therefore, in the definition of the CheckedPtrToT class, we must provide separate functions for the prefix and postfix increment and decrement operations:

class CheckedPtrToT {

T * p;

T * array;

int size;

public:

// initial value `p '

// bind to array `a 'of size` s'

CheckedPtrTo T (T * p, T * a, int s);

// initial value `p '

// bind to a single object

CheckedPtrToT (T * p);

T * operator ++ (); // prefix

T * operator ++ (int); // postfix

T * operator - (); // prefix

T * operator - (int); // postfix

T & operator * (); // prefix

};

A parameter of type int serves as an indication that the function will be called for a postfix operation. In fact, this parameter is artificial and never used, but only serves to distinguish between postfix and prefix operations. To remember which version of the operator ++ function is used as a prefix operation, it is enough to remember that the prefix is ​​the version without an artificial parameter, which is true for all other unary arithmetic and logical operations. The artificial parameter is used only for "special" postfix operations ++ and -. Using the CheckedPtrToT class, an example can be written like this:

void f3 (T a) // variant with control

{

T v [200];

CheckedPtrToT p (& v [0], v, 200);

p.operator - (1);

p.operator * () = a; // dynamic error:

// `p 'out of bounds of array

p.operator ++ ();

p.operator * () = a; // fine

}

Exercise $$ 7.14 [19] proposes to complete the definition of the CheckedPtrToT class , and another exercise ($$ 9.10 [2]) is to convert it to a type template that uses exceptions to report dynamic errors. Examples of using ++ and - for iterations can be found in $$ 8.8.

7.11 String class

Now we can bring a more meaningful version of the string class. It counts the number of references per string to minimize copying and uses standard C ++ strings as constants.

#include <iostream.h>

#include <string.h>

class string {

struct srep {

char * s; // pointer to string

int n; // reference count

srep () {n = 1; }

};

srep * p;

public:

string (const char *); // string x = "abc"

string (); // string x;

string (const string &); // string x = string ...

string & operator = (const char *);

string & operator = (const string &);

~ string ();

char & operator [] (int i);

friend ostream & operator << (ostream &, const string &);

friend istream & operator >> (istream &, string &);

friend int operator == (const string & x, const char * s)

{return strcmp (xp-> s, s) == 0; }

friend int operator == (const string & x, const string & y)

{return strcmp (xp-> s, yp-> s) == 0; }

friend int operator! = (const string & x, const char * s)

{return strcmp (xp-> s, s)! = 0; }

friend int operator!

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.