XCode error message

[Monroe]

Hello,

I am brand new at programming and I'm studying C++ on my own. I set up an XCode project, but I'm stuck with several error messages. When replying, please keep in mind that I have never programmed in any language and I'm a complete beginner.

Thanks :)

  #ifdef _MSC_VER
#include <hash_map>
using stdext::hash_map;
#else
#include <ext/hash_map>
using __gnu_cxx::hash_map;

namespace __gnu_cxx {
    
    template<> struct hash<std::string>
    {
        size_t operator()(const std::string& s) const
        {
            return hash<char*>()(s.c_str());
        }
    };
    
} // of namespace __gnu_cxx
#endif

//------------------------------------------------------------------------------

#define unordered_map hash_map

//------------------------------------------------------------------------------

typedef long Unicode;

//------------------------------------------------------------------------------

using namespace std;

template<class T> string to_string(const T& t)
{
	ostringstream os;
	os << t;
	return os.str();
}

struct Range_error : out_of_range {	// enhanced vector range error reporting
	int index;
	Range_error(int i) :out_of_range("Range error: "+to_string(i)), index(i) { }
};


// trivially range-checked vector (no iterator checking):
template< class T> struct Vector : public std::vector<T> {
	typedef typename std::vector<T>::size_type size_type;
    
	Vector() { }
	explicit Vector(size_type n) :std::vector<T>(n) {}
	Vector(size_type n, const T& v) :std::vector<T>(n,v) {}
	template <class I>
	Vector(I first, I last) :std::vector<T>(first,last) {}
    
	T& operator[](unsigned int i) // rather than return at(i);
	{
		if (i<0||this->size()<=i) throw Range_error(i);
		return std::vector<T>::operator[](i);
	}
	const T& operator[](unsigned int i) const
	{
		if (i<0||this->size()<=i) throw Range_error(i);
		return std::vector<T>::operator[](i);
	}
};

// disgusting macro hack to get a range checked vector:
#define vector Vector

// trivially range-checked string (no iterator checking):
struct String : std::string {
	
	String() { }
	String(const char* p) :std::string(p) {}
	String(const string& s) :std::string(s) {}
	template<class S> String(S s) :std::string(s) {}
	String(int sz, char val) :std::string(sz,val) {}
	template<class Iter> String(Iter p1, Iter p2) : std::string(p1,p2) { }
    
	char& operator[](unsigned int i) // rather than return at(i);
	{
		if (i<0||size()<=i) throw Range_error(i);
		return std::string::operator[](i);
	}
    
	const char& operator[](unsigned int i) const
	{
		if (i<0||size()<=i) throw Range_error(i);
		return std::string::operator[](i);
	}
};

#ifndef _MSC_VER
namespace __gnu_cxx {
    
    template<> struct hash<String>
    {
        size_t operator()(const String& s) const
        {
            return hash<std::string>()(s);
        }
    };
    
} // of namespace __gnu_cxx
#endif


struct Exit : runtime_error {
	Exit(): runtime_error("Exit") {}
};

// error() simply disguises throws:
inline void error(const string& s)
{
	throw runtime_error(s);
}

inline void error(const string& s, const string& s2)
{
	error(s+s2);
}

inline void error(const string& s, int i)
{
	ostringstream os;
	os << s <<": " << i;
	error(os.str());
}

#if _MSC_VER<1500
// disgusting macro hack to get a range checked string:
#define string String
// MS C++ 9.0 have a built-in assert for string range check
// and uses "std::string" in several places so that macro substitution fails
#endif

template<class T> char* as_bytes(T& i)	// needed for binary I/O
{
	void* addr = &i;	// get the address of the first byte
    // of memory used to store the object
	return static_cast<char*>(addr); // treat that memory as bytes
}


/*inline void keep_window_open()
{
	cin.clear();
	cout << "Please enter a character to exit\n";
	char ch;
	cin >> ch;
	return;
}

inline void keep_window_open(string s)
{
	if (s=="") return;
	cin.clear();
	cin.ignore(120,'\n');
	for (;;)/> {
		cout << "Please enter " << s << " to exit\n";
		string ss;
		while (cin >> ss && ss!=s)
			cout << "Please enter " << s << " to exit\n";
		return;
	}
}*/



// error function to be used (only) until error() is introduced in Chapter 5:
inline void simple_error(string s)	// write ``error: s�� and exit program
{
	cerr << "error: " << s << '\n';
	//Commented out: keep_window_open();		// for some Windows environments
	exit(1);
}

// make std::min() and std::max() accessible:
#undef min
#undef max

#include<iomanip>
inline ios_base& general(ios_base& B)/>	// to augment fixed and scientific
{
	b.setf(ios_base::fmtflags(0),ios_base::floatfield);
	return b;
}

// run-time checked narrowing cast (type conversion):
template<class R, class A> R narrow_cast(const A& a)
{
	R r = R(a);
	if (A(r)!=a) error(string("info loss"));
	return r;
}


inline int randint(int max) { return rand()%max; }

inline int randint(int min, int max) { return randint(max-min)+min; }

inline double sqrt(int x) { return sqrt(double(x)); }	// to match C++0x

#endif

1. SEMANTIC ERROR MESSAGE: "No matching function for call to object of type 'hash<char*>'
for line: return hash<char*>()(s.c_str());

2. SEMANTIC ERROR MESSAGE: "Comparison of unsigned expression <0 is always false."
for both lines that state: if (i<0||size()<=i) throw Range_error(i);
13 return std::string::operator[](i);

[coder777]

I don't know what the hash problem refers to. Since it isn't used you may just remove it.

For the second problem: i cannot be less than 0 due to its unsigned nature. Just remove the i<0 part of the expression.

All in all it's over complicated and not very suitable for a beginner.

[Cody0023]

Hard to believe you can be a complete beginner and write this.

[Jaybob66]

@Monroe

this code appears to be copied from the web http://www.stroustrup.com/Programming/std_lib_facilities.h


You have only given us half the story here, where is your code that generates the error?

Cut and paste the FULL error message you are getting, not just the bit you think we are interested in.

[Monroe]

@jaybob66

Thanks for the response. Yes, I got the code from the website you specified. It's a part of an assignment in a book I'm studying to learn C++.

I did post the full error messages right below the code, along with the lines generating the errors. To be specific, the errors are found in these lines:

line 14: "No matching function for call to object of type 'hash<char*>"

lines 58-59 and 63-64 have the same error message: ""Comparison of unsigned expression <0 is always false."

[giblit]

If you are a beginner I would suggest you start with the basics and not jump to templates, pointers, references, containers, macros, ect.. Anyways this code seems overly complicated.

These tutorials may help you:
http://www.cplusplus.com/doc/tutorial/
http://www.learncpp.com/
http://www.parashift.com/c++-faq/ <--when you get to classes/structures

line 14: "No matching function for call to object of type 'hash<char*>"

I believe you want hash<std::string>()(s). Since you never made the char pointer overload. Also is this all one file? I find it odd to have std::prefix for some and using namespace std; for the rest.

lines 58-59 and 63-64 have the same error message: ""Comparison of unsigned expression <0 is always false."

unsigned is 0 or greater so checking if it is less than 0 is not necessary. Basically if you had a signed 32 bit number that would mean it goes from 0->2^32 - 1 and if it is signed it goes from -2^31-1 -> 2^31-1 (the first bit is used for the sign positive/negative)