please help me to solve this problem, thanks. I am newcomer to C++

S

Simon

platform: Borland C++ 5.5 free Winxp

C++ source from: C++ primer Plus 5 Edition.

Complie Error: "operator >>" not implemented in type 'istream' for
arguments of type "STRING" in function main()


//mystring.h
#ifndef MYSTRING_H_
#define MYSTRING_H_
#include <iostream.h>

using std::eek:stream;
using std::istream;

class STRING
{
private:
char *str;
int len;
static int num_strings;
static const int CINLIM=80;
public:
STRING(const char *s); //constructor
STRING(); //default constructor
STRING(const STRING &);// copy constructor
~STRING();
int length()const { return len; }
//overload operator methods
STRING &operator=(const STRING &);
STRING &operator=(const char *);
char &operator[] (int i);
const char &operator[] (int i)const;
//overload operator friends
friend bool operator<(const STRING &st, const STRING &st2);
friend bool operator>(const STRING &st1, const STRING &st2);
friend bool operator==(const STRING &st, const STRING &st2);
friend ostream &operator<<(ostream &os, const STRING &st);
friend istream &operator>>(istream *is, STRING &st);
//static function
static int HowMany();
};
#endif

//mystring.cpp

#include <cstring.h>
#include <string.h>
#include "mystring.h"

using std::cin;
using std::cout;

int STRING::num_strings=0;

int STRING::HowMany()
{
return num_strings;
}
//class methods

STRING::STRING(const char *s)
{
len=std::strlen(s);
str=new char[len+1];
std::strcpy(str,s);
num_strings++;
}

STRING::STRING()
{
len=4;
str=new char[1];
str[0]='\0';
num_strings++;
}
STRING::STRING(const STRING &st)
{
num_strings++;
len=st.len;
str=new char[len+1];
std::strcpy(str,st.str);
}

STRING::~STRING()
{
--num_strings;
delete [] str;
}
//overload operator methods
//assign a STRING to a STRING
STRING & STRING::eek:perator=(const STRING &st)
{
if(this==&st)
return *this;
delete [] str;
len=st.len;
str=new char[len+1];
std::strcpy(str, st.str);
return *this;
}
// assign a C string to a string
STRING &STRING::eek:perator=(const char *s)
{
delete [] str;
len=std::strlen(s);
str=new char[len+1];
std::strcpy(str,s);
return *this;
}
char &STRING::eek:perator[] (int i)
{
return str;
}
const char &STRING::eek:perator[] (int i)const
{
return str;
}
bool operator<(const STRING &st1, const STRING &st2)
{
return (std::strcmp(st1.str, st2.str)<0);
}
bool operator>(const STRING &st1, const STRING &st2)
{
return st2.str<st1.str;
}
bool operator==(const STRING &st1, const STRING &st2)
{
return (std::strcmp(st1.str, st2.str)==0);
}
ostream &operator<<(ostream &os, const STRING &st)
{
os<<st.str;
return os;
}

istream & operator>> (istream & is, STRING &st)
{
char temp[STRING::CINLIM];

is.get(temp, STRING::CINLIM);

if(is)
st=temp;
while(is && is.get()!='\n')
continue;
return is;

}


//mysaying.cpp

#include <iostream.h>
#include "mystring.h"
const int ArSize=10;
const int MaxLen=81;


int main()
{
using std::cout;
using std::cin;
using std::endl;
STRING name;
cout<<"Hi, what's your name?\n>>";
cin >> name;

cout<<name<<", please enter up to "<<ArSize
<<"short sayings<empty line to quit>:\n";
STRING sayings[ArSize];
char temp[MaxLen];
int i;
for(i=0;i<ArSize;i++)
{
cout<<i+1<<": ";
cin.get(temp,MaxLen);
while(cin &&cin.get()!='\n')
continue;
if(!cin||temp[0]=='\n') //empty line
break;
else
sayings=temp; //overload assignment
}
int total=i;
cout<<"Here are you sayings:\n";
for(i=0;i<total;i++)
cout<<sayings[0]<<": "<<sayings<<endl;
int shortest=0;
int first=0;
for(i=1;i<total;i++)
{
if(sayings.length()<sayings[shortest].length())
shortest=i;
if(sayings<sayings[first])
first=i;
}
cout<<"Shortest saying:\n"<<sayings[shortest]<<endl;
cout<<"First aphabetically:\n"<<sayings[first]<<endl;
cout<<"This program used "<<STRING::HowMany()
<<"STRING objects/Bye.\n";
return 0;


}
 
I

Ian Collins

Simon said:
platform: Borland C++ 5.5 free Winxp

C++ source from: C++ primer Plus 5 Edition.

Complie Error: "operator >>" not implemented in type 'istream' for
arguments of type "STRING" in function main()


//mystring.h
#ifndef MYSTRING_H_
#define MYSTRING_H_
#include <iostream.h>

using std::eek:stream;
using std::istream;
Click to expand...
Putting 'using' in headers is no-no, it gets dragged into any file that
includes the header.
class STRING
Click to expand...

Avoid all caps for class names, the idiomatic use for all caps is for
macros.

friend istream &operator>>(istream *is, STRING &st);
Click to expand...
^^
There's your problem, should be istream&.
//static function
Click to expand...

Silly comment!
 
R

red floyd

Simon said:
platform: Borland C++ 5.5 free Winxp

C++ source from: C++ primer Plus 5 Edition.

Complie Error: "operator >>" not implemented in type 'istream' for
arguments of type "STRING" in function main()


//mystring.h
#ifndef MYSTRING_H_
#define MYSTRING_H_
#include <iostream.h>
Click to expand...
Non-standard include. You should use
#include <iostream>

Actually, since you never use a full iostream, just references, you
should use

#include said:
using std::eek:stream;
using std::istream;

class STRING
{
private:
char *str;
int len;
static int num_strings;
static const int CINLIM=80;
public:
STRING(const char *s); //constructor
STRING(); //default constructor
STRING(const STRING &);// copy constructor
~STRING();
int length()const { return len; }
//overload operator methods
STRING &operator=(const STRING &);
STRING &operator=(const char *);
char &operator[] (int i);
const char &operator[] (int i)const;
//overload operator friends
friend bool operator<(const STRING &st, const STRING &st2);
friend bool operator>(const STRING &st1, const STRING &st2);
friend bool operator==(const STRING &st, const STRING &st2);
friend ostream &operator<<(ostream &os, const STRING &st);
friend istream &operator>>(istream *is, STRING &st);
//static function
static int HowMany();
};
#endif

//mystring.cpp

#include <cstring.h>
#include <string.h>
#include "mystring.h"

using std::cin;
using std::cout;

int STRING::num_strings=0;

int STRING::HowMany()
{
return num_strings;
}
//class methods

STRING::STRING(const char *s)
{
len=std::strlen(s);
str=new char[len+1];
std::strcpy(str,s);
num_strings++;
}

STRING::STRING()
{
len=4;
str=new char[1];
str[0]='\0';
num_strings++;
}
STRING::STRING(const STRING &st)
{
num_strings++;
len=st.len;
str=new char[len+1];
std::strcpy(str,st.str);
}

STRING::~STRING()
{
--num_strings;
delete [] str;
}
//overload operator methods
//assign a STRING to a STRING
STRING & STRING::eek:perator=(const STRING &st)
{
if(this==&st)
return *this;
delete [] str;
len=st.len;
str=new char[len+1];
std::strcpy(str, st.str);
return *this;
}
// assign a C string to a string
STRING &STRING::eek:perator=(const char *s)
{
delete [] str;
len=std::strlen(s);
str=new char[len+1];
std::strcpy(str,s);
return *this;
}
char &STRING::eek:perator[] (int i)
{
return str;
}
const char &STRING::eek:perator[] (int i)const
{
return str;
}
bool operator<(const STRING &st1, const STRING &st2)
{
return (std::strcmp(st1.str, st2.str)<0);
}
bool operator>(const STRING &st1, const STRING &st2)
{
return st2.str<st1.str;
}
bool operator==(const STRING &st1, const STRING &st2)
{
return (std::strcmp(st1.str, st2.str)==0);
}
ostream &operator<<(ostream &os, const STRING &st)
{
os<<st.str;
return os;
}

istream & operator>> (istream & is, STRING &st)
{
char temp[STRING::CINLIM];

is.get(temp, STRING::CINLIM);

if(is)
st=temp;
while(is && is.get()!='\n')
continue;
return is;

}


//mysaying.cpp

#include <iostream.h>
#include "mystring.h"
const int ArSize=10;
const int MaxLen=81;


int main()
{
using std::cout;
using std::cin;
using std::endl;
STRING name;
cout<<"Hi, what's your name?\n>>";
cin >> name;

cout<<name<<", please enter up to "<<ArSize
<<"short sayings<empty line to quit>:\n";
STRING sayings[ArSize];
char temp[MaxLen];
int i;
for(i=0;i<ArSize;i++)
{
cout<<i+1<<": ";
cin.get(temp,MaxLen);
while(cin &&cin.get()!='\n')
continue;
if(!cin||temp[0]=='\n') //empty line
break;
else
sayings=temp; //overload assignment
}
int total=i;
cout<<"Here are you sayings:\n";
for(i=0;i<total;i++)
cout<<sayings[0]<<": "<<sayings<<endl;
int shortest=0;
int first=0;
for(i=1;i<total;i++)
{
if(sayings.length()<sayings[shortest].length())
shortest=i;
if(sayings<sayings[first])
first=i;
}
cout<<"Shortest saying:\n"<<sayings[shortest]<<endl;
cout<<"First aphabetically:\n"<<sayings[first]<<endl;
cout<<"This program used "<<STRING::HowMany()
<<"STRING objects/Bye.\n";
return 0;


}
Click to expand...
 

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