ميگه نبايد به اشاره گرها آدرس تخصيص بديم
پس چرا تو خط76کد:itsString[i] = rhs[i];
بجاي اينكه به آرايه ي اشاره گر iitsString آدرسهاي rhs را تخصيص بده مقدار تخصيص داده؟
کد:// Listing 16.1 The String Class
#include <iostream>
#include <string.h>
using namespace std;
class String
{
public:
// constructors
String();
String(const char *const);
String(const String &);
~String();
// overloaded operators
char & operator[](int offset);
char operator[](int offset) const;
String operator+(const String&);
void operator+=(const String&);
String & operator= (const String &);
// General accessors
int GetLen()const { return itsLen; }
const char * GetString() const { return itsString; }
// static int ConstructorCount;
private:
String (int); // private constructor
char * itsString;
unsigned short itsLen;
};
// default constructor creates string of 0 bytes
String::String()
{
itsString = new char[1];
itsString[0] = '\0';
itsLen=0;
// cout << "\tDefault string constructor\n";
// ConstructorCount++;
}
// private (helper) constructor, used only by
// class methods for creating a new string of
// required size. Null filled.
String::String(int len)
{
itsString = new char[len+1];
for (int i = 0; i<=len; i++)
itsString[i] = '\0';
itsLen=len;
// cout << "\tString(int) constructor\n";
// ConstructorCount++;
}
// Converts a character array to a String
String::String(const char * const cString)
{
itsLen = strlen(cString);
itsString = new char[itsLen+1];
for (int i = 0; i<itsLen; i++)
itsString[i] = cString[i];
itsString[itsLen]='\0';
// cout << "\tString(char*) constructor\n";
// ConstructorCount++;
}
// copy constructor
String::String (const String & rhs)
{
itsLen=rhs.GetLen();
itsString = new char[itsLen+1];
for (int i = 0; i<itsLen;i++)
itsString[i] = rhs[i];
itsString[itsLen] = '\0';
// cout << "\tString(String&) constructor\n";
// ConstructorCount++;
}
// destructor, frees allocated memory
String::~String ()
{
delete [] itsString;
itsLen = 0;
// cout << "\tString destructor\n";
}
// operator equals, frees existing memory
// then copies string and size
String& String::operator=(const String & rhs)
{
if (this == &rhs)
return *this;
delete [] itsString;
itsLen=rhs.GetLen();
itsString = new char[itsLen+1];
for (int i = 0; i<itsLen;i++)
itsString[i] = rhs[i];
itsString[itsLen] = '\0';
return *this;
// cout << "\tString operator=\n";
}
//non constant offset operator, returns
// reference to character so it can be
// changed!
char & String::operator[](int offset)
{
if (offset > itsLen)
return itsString[itsLen-1];
else
return itsString[offset];
}
// constant offset operator for use
// on const objects (see copy constructor!)
char String::operator[](int offset) const
{
if (offset > itsLen)
return itsString[itsLen-1];
else
return itsString[offset];
}
// creates a new string by adding current
// string to rhs
String String::operator+(const String& rhs)
{
int totalLen = itsLen + rhs.GetLen();
String temp(totalLen);
int i, j;
for (i = 0; i<itsLen; i++)
temp[i] = itsString[i];
for (j = 0; j<rhs.GetLen(); j++, i++)
temp[i] = rhs[j];
temp[totalLen]='\0';
return temp;
}
// changes current string, returns nothing
void String::operator+=(const String& rhs)
{
unsigned short rhsLen = rhs.GetLen();
unsigned short totalLen = itsLen + rhsLen;
String temp(totalLen);
int i, j;
for (i = 0; i<itsLen; i++)
temp[i] = itsString[i];
for (j = 0; j<rhs.GetLen(); j++, i++)
temp[i] = rhs[i-itsLen];
temp[totalLen]='\0';
*this = temp;
}
// int String::ConstructorCount = 0;
