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Compile error.

P: n/a
This is an simple map, just an exercise. Who can help me fix this
compile issue?Thanks in advance.
#include <string>
#include <vector>
#include <iostream>
using std::vector;
using std::string;
using std::cout;
using std::endl;

template<typename T>
class Map{
template<typename U>
struct Pair{
string name;
U val;
Pair(string n ="", U v):name(n),val(v){}
};
vector<Pair<T vec;
Map(const Map&);
Map& operator=(const Map&);
typedef vector<Pair<T::const_iterator CIT;
typedef vector<Pair<T::iterator IT;
public:
Map(){}
double& operator[](const string&);
void print_all()const;
};
template<typename T>
T& Map<T>::operator[](const string& name)
{
IT it = vec.begin();
IT end = vec.end();
for(; it != end; ++it){
if(it->name == name) return it->val;
}
vec.push_back(Pair<T>(name,T()));
return vec.back().val;
}
template<typename T>
void Map<T>::print_all()const
{
for(CIT p = vec.begin(); p != vec.end();++p){
cout << p->name << ": " << p->val << endl;
}
}
int main()
{
Map<intm;
m["zhu"] = 100;
m["li"] = 200;
m.print_all();
}
-*- mode: compilation; default-directory: "e:/tcplex/p2_ch13/" -*-
Compilation started at Sat Nov 15 21:42:28

g++ 13.8.cpp
13.8.cpp:20: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:20: error: ISO C++ forbids declaration of `const_iterator'
with no type
13.8.cpp:20: error: expected `;' before "CIT"
13.8.cpp:21: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:21: error: ISO C++ forbids declaration of `iterator' with no
type
13.8.cpp:21: error: expected `;' before "IT"
13.8.cpp:29: error: prototype for `T& Map<T>::operator[](const
std::string&)' does not match any in class `Map<T>'
13.8.cpp:24: error: candidate is: double& Map<T>::operator[](const
std::string&)
13.8.cpp:29: error: template definition of non-template `T&
Map<T>::operator[](const std::string&)'
13.8.cpp: In member function `T& Map<T>::operator[](const
std::string&)':
13.8.cpp:30: error: `IT' was not declared in this scope
13.8.cpp:30: error: expected `;' before "it"
13.8.cpp:31: error: expected `;' before "end"
13.8.cpp:32: error: `it' was not declared in this scope
13.8.cpp:32: error: `end' was not declared in this scope
13.8.cpp: In member function `void Map<T>::print_all() const':
13.8.cpp:41: error: `CIT' was not declared in this scope
13.8.cpp:41: error: expected `;' before "p"
13.8.cpp:41: error: `p' was not declared in this scope

Compilation exited abnormally with code 1 at Sat Nov 15 21:42:28


Nov 15 '08 #1
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3 Replies


P: n/a
On 11月15日, 下午9时43分, Hill <zhubi...@gmail.com>wrote:
This is an simple map, just an exercise. Who can help me fix this
compile issue?Thanks in advance.
#include <string>
#include <vector>
#include <iostream>
using std::vector;
using std::string;
using std::cout;
using std::endl;

template<typename T>
class Map{
template<typename U>
struct Pair{
string name;
U val;
Pair(string n ="", U v):name(n),val(v){}
};
vector<Pair<T vec;
Map(const Map&);
Map& operator=(const Map&);
typedef vector<Pair<T::const_iterator CIT;
typedef vector<Pair<T::iterator IT;
const_iterator is a dependent type here,
try
typedef typename vector<Pair<T::const_iterator CIT;
typedef typename vector<Pair<T::iterator IT;
public:
Map(){}
double& operator[](const string&);
void print_all()const;};

template<typename T>
T& Map<T>::operator[](const string& name)
{
IT it = vec.begin();
IT end = vec.end();
for(; it != end; ++it){
if(it->name == name) return it->val;
}
vec.push_back(Pair<T>(name,T()));
return vec.back().val;}

template<typename T>
void Map<T>::print_all()const
{
for(CIT p = vec.begin(); p != vec.end();++p){
cout << p->name << ": " << p->val << endl;
}}

int main()
{
Map<intm;
m["zhu"] = 100;
m["li"] = 200;
m.print_all();

}

-*- mode: compilation; default-directory: "e:/tcplex/p2_ch13/" -*-
Compilation started at Sat Nov 15 21:42:28

g++ 13.8.cpp
13.8.cpp:20: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:20: error: ISO C++ forbids declaration of `const_iterator'
with no type
13.8.cpp:20: error: expected `;' before "CIT"
13.8.cpp:21: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:21: error: ISO C++ forbids declaration of `iterator' with no
type
13.8.cpp:21: error: expected `;' before "IT"
13.8.cpp:29: error: prototype for `T& Map<T>::operator[](const
std::string&)' does not match any in class `Map<T>'
13.8.cpp:24: error: candidate is: double& Map<T>::operator[](const
std::string&)
13.8.cpp:29: error: template definition of non-template `T&
Map<T>::operator[](const std::string&)'
13.8.cpp: In member function `T& Map<T>::operator[](const
std::string&)':
13.8.cpp:30: error: `IT' was not declared in this scope
13.8.cpp:30: error: expected `;' before "it"
13.8.cpp:31: error: expected `;' before "end"
13.8.cpp:32: error: `it' was not declared in this scope
13.8.cpp:32: error: `end' was not declared in this scope
13.8.cpp: In member function `void Map<T>::print_all() const':
13.8.cpp:41: error: `CIT' was not declared in this scope
13.8.cpp:41: error: expected `;' before "p"
13.8.cpp:41: error: `p' was not declared in this scope

Compilation exited abnormally with code 1 at Sat Nov 15 21:42:28
Nov 15 '08 #2

P: n/a
On 11月15日, 下午10时54分, Barry <dhb2...@gmail.comwrote:
On 11月15日, 下午9时43分, Hill <zhubi...@gmail.comwrote:
This is an simple map, just an exercise. Who can help me fix this
compile issue?Thanks in advance.
#include <string>
#include <vector>
#include <iostream>
using std::vector;
using std::string;
using std::cout;
using std::endl;
template<typename T>
class Map{
template<typename U>
struct Pair{
string name;
U val;
Pair(string n ="", U v):name(n),val(v){}
};
vector<Pair<T vec;
Map(const Map&);
Map& operator=(const Map&);
typedef vector<Pair<T::const_iterator CIT;
typedef vector<Pair<T::iterator IT;

const_iterator is a dependent type here,
try
typedef typename vector<Pair<T::const_iterator CIT;
typedef typename vector<Pair<T::iterator IT;
public:
Map(){}
double& operator[](const string&);
void print_all()const;};
template<typename T>
T& Map<T>::operator[](const string& name)
{
IT it = vec.begin();
IT end = vec.end();
for(; it != end; ++it){
if(it->name == name) return it->val;
}
vec.push_back(Pair<T>(name,T()));
return vec.back().val;}
template<typename T>
void Map<T>::print_all()const
{
for(CIT p = vec.begin(); p != vec.end();++p){
cout << p->name << ": " << p->val << endl;
}}
int main()
{
Map<intm;
m["zhu"] = 100;
m["li"] = 200;
m.print_all();
}
-*- mode: compilation; default-directory: "e:/tcplex/p2_ch13/" -*-
Compilation started at Sat Nov 15 21:42:28
g++ 13.8.cpp
13.8.cpp:20: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:20: error: ISO C++ forbids declaration of `const_iterator'
with no type
13.8.cpp:20: error: expected `;' before "CIT"
13.8.cpp:21: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:21: error: ISO C++ forbids declaration of `iterator' with no
type
13.8.cpp:21: error: expected `;' before "IT"
13.8.cpp:29: error: prototype for `T& Map<T>::operator[](const
std::string&)' does not match any in class `Map<T>'
13.8.cpp:24: error: candidate is: double& Map<T>::operator[](const
std::string&)
13.8.cpp:29: error: template definition of non-template `T&
Map<T>::operator[](const std::string&)'
13.8.cpp: In member function `T& Map<T>::operator[](const
std::string&)':
13.8.cpp:30: error: `IT' was not declared in this scope
13.8.cpp:30: error: expected `;' before "it"
13.8.cpp:31: error: expected `;' before "end"
13.8.cpp:32: error: `it' was not declared in this scope
13.8.cpp:32: error: `end' was not declared in this scope
13.8.cpp: In member function `void Map<T>::print_all() const':
13.8.cpp:41: error: `CIT' was not declared in this scope
13.8.cpp:41: error: expected `;' before "p"
13.8.cpp:41: error: `p' was not declared in this scope
Compilation exited abnormally with code 1 at Sat Nov 15 21:42:28

Thanks very much.
But now i upgrade the code to let it can hold types without default
constructor. But caught in another error:
#include <string>
#include <vector>
#include <iostream>
using std::vector;
using std::string;
using std::cout;
using std::endl;
using std::ostream;

template<typename T>
struct Aligner{
union{
long double long_double_;
long long_;
void (*simple_function_ptr)();
};
};

template<typename T>
class Map{
template<typename U>
struct Pair{
string name;
union{
char raw_mem[sizeof(U)];
Aligner<Udummy;
}val;
Pair(string n = ""):name(n){}

Pair& operator=(const U& v){
new(val.raw_mem) U(v);
return *this;
}
};
vector<Pair<T vec;
Map(const Map&);
Map& operator=(const Map&);
typedef typename vector<Pair<T::const_iterator CIT;
typedef typename vector<Pair<T::iterator IT;
public:
Map(){}
Pair<T>& operator[](const string&);
void print_all()const;
};
template<typename T>
Pair<T>& Map<T>::operator[](const string&
name)////////////////////////////line 46
{
IT it = vec.begin();
IT end = vec.end();
for(; it != end; ++it){
if(it->name == name) return *it;
}
vec.push_back(Pair<T>(name));
return vec.back();
}
template<typename T>
void Map<T>::print_all()const
{
for(CIT p = vec.begin(); p != vec.end();++p){
cout << p->name << ": " << *(T*)(&p->val.raw_mem[0]) << endl;
}
}
struct stu{
string name;
string id;
stu(string n, string i):name(n), id(i){}
//stu(){}
};
ostream& operator<<(ostream& os, const stu& s)
{
return os << " Name: " << s.name << " Id: " << s.id ;
}

int main()
{
Map<stum;
m["first"] = stu("Zhubicen","011062");
m.print_all();
}

-*- mode: compilation; default-directory: "z:/tcplex/p2_ch13/" -*-
Compilation started at Sun Nov 16 19:33:03

g++ 13.8.cpp
13.8.cpp:46: error: expected constructor, destructor, or type
conversion before '<' token

Compilation exited abnormally with code 1 at Sun Nov 16 19:33:03



Nov 16 '08 #3

P: n/a
On Nov 15, 6:43 pm, Hill <zhubi...@gmail.comwrote:
This is an simple map, just an exercise. Who can help me fix this
compile issue?Thanks in advance.
#include <string>
#include <vector>
#include <iostream>
using std::vector;
using std::string;
using std::cout;
using std::endl;

template<typename T>
class Map{
template<typename U>
struct Pair{
string name;
U val;
Pair(string n ="", U v):name(n),val(v){}
};
vector<Pair<T vec;
Map(const Map&);
Map& operator=(const Map&);
typedef vector<Pair<T::const_iterator CIT;
typedef vector<Pair<T::iterator IT;
public:
Map(){}
double& operator[](const string&);
void print_all()const;};

template<typename T>
T& Map<T>::operator[](const string& name)
{
IT it = vec.begin();
IT end = vec.end();
for(; it != end; ++it){
if(it->name == name) return it->val;
}
vec.push_back(Pair<T>(name,T()));
return vec.back().val;}

template<typename T>
void Map<T>::print_all()const
{
for(CIT p = vec.begin(); p != vec.end();++p){
cout << p->name << ": " << p->val << endl;
}}

int main()
{
Map<intm;
m["zhu"] = 100;
m["li"] = 200;
m.print_all();

}

-*- mode: compilation; default-directory: "e:/tcplex/p2_ch13/" -*-
Compilation started at Sat Nov 15 21:42:28

g++ 13.8.cpp
13.8.cpp:20: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:20: error: ISO C++ forbids declaration of `const_iterator'
with no type
13.8.cpp:20: error: expected `;' before "CIT"
13.8.cpp:21: error: type `std::vector<Map<T>::Pair<T>,
std::allocator<Map<T>::Pair<T >' is not derived from type `Map<T>'
13.8.cpp:21: error: ISO C++ forbids declaration of `iterator' with no
type
13.8.cpp:21: error: expected `;' before "IT"
13.8.cpp:29: error: prototype for `T& Map<T>::operator[](const
std::string&)' does not match any in class `Map<T>'
13.8.cpp:24: error: candidate is: double& Map<T>::operator[](const
std::string&)
13.8.cpp:29: error: template definition of non-template `T&
Map<T>::operator[](const std::string&)'
13.8.cpp: In member function `T& Map<T>::operator[](const
std::string&)':
13.8.cpp:30: error: `IT' was not declared in this scope
13.8.cpp:30: error: expected `;' before "it"
13.8.cpp:31: error: expected `;' before "end"
13.8.cpp:32: error: `it' was not declared in this scope
13.8.cpp:32: error: `end' was not declared in this scope
13.8.cpp: In member function `void Map<T>::print_all() const':
13.8.cpp:41: error: `CIT' was not declared in this scope
13.8.cpp:41: error: expected `;' before "p"
13.8.cpp:41: error: `p' was not declared in this scope

Compilation exited abnormally with code 1 at Sat Nov 15 21:42:28
In your code if type U is not specially treated than type T as well as
it is directly dependent on type T then why did you introduce type U.
Better to remove it.

template<typename T>
class Map{
struct Pair{
string name;
T val;
Pair(string n ="", U v):name(n),val(v){}
};
vector<Pairvec;
Pair(string n ="", U v)
In this definition you're providing default argument from left side
which is not acceptable at all according to C++.
typedef vector<Pair<T::const_iterator CIT;
In this statement you're missing typename keyword. Use the following
statement
typedef typename vector<Pair<T::const_iterator CIT;
double& operator[](const string&);
Why return type is double???

Check all these things and your compilation error will be removed.
--
Daya
Nov 17 '08 #4

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