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Jun 1st, 2009

Convert Custom type 'String' to std::string

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EDIT: I mucked up the thread title. It should be "Convert Custom type 'String' to std::string"

Hi,

How would I be able to convert a custom type 'String' to a std::string? Just that the function I'm using requires a std::string.

troublesome code:

C++ Syntax (Toggle Plain Text)
SetVar::operator char* ()
{
	if (szName == "Passwd")//only create a md5 hash for the password, not anything else
	{
		std::string pwd;
		//here i need to convert 'sVal' from a String to a std::string called 'pwd'
		return md5.getHashFromString(pwd);
	}
	return sVal;
}
SetVar::operator char* ()
{
	if (szName == "Passwd")//only create a md5 hash for the password, not anything else
	{
		std::string pwd;
		//here i need to convert 'sVal' from a String to a std::string called 'pwd'
		return md5.getHashFromString(pwd);
	}
	return sVal;
}

types.cpp

C++ Syntax (Toggle Plain Text)
// types.cpp
//
 
#include "types.h"
 
//
// String
//
 
String::String()
{
	szStr = NULL;
}
 
String::String(char *str)
{
	*this = str;
}
 
String::~String()
{
	if (szStr) {
		free(szStr);
		szStr = NULL;
	}
}
 
String& String::operator= (char *str)
{
	if (szStr) {
		free(szStr);
		szStr = NULL;
	}
 
	if (str)
		szStr = strdup(str);
 
	return *this;
}
 
String::operator char* ()
{
	return szStr;
}
 
bool String::operator== (char *str)
{
	if (!strcmp(szStr, str))
		return true;
	else
		return false;
}
// types.cpp
//

#include "types.h"

//
// String
//

String::String()
{
	szStr = NULL;
}

String::String(char *str)
{
	*this = str;
}

String::~String()
{
	if (szStr) {
		free(szStr);
		szStr = NULL;
	}
}

String& String::operator= (char *str)
{
	if (szStr) {
		free(szStr);
		szStr = NULL;
	}

	if (str)
		szStr = strdup(str);
	
	return *this;
}

String::operator char* ()
{
	return szStr;
}

bool String::operator== (char *str)
{
	if (!strcmp(szStr, str))
		return true;
	else
		return false;
}

types.h

C++ Syntax (Toggle Plain Text)
// types.h
//
 
#ifndef TTYPES_H
#define TTYPES_H
 
#include <windows.h>
 
typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
 
#define WSTD_DEL(x) { if ((x)) { delete (x); (x)=NULL; } }
#define WSTD_DELM(x) { if ((x)) { delete[] (x); (x)=NULL; } }
 
//
// String
//
 
class String
{
	public:
		String();
		String(char *str);
		~String();
 
		String& operator= (char *str);
		operator char* ();
 
		bool operator== (char *str);
 
	private:
		char *szStr;
};
 
#endif
// types.h
//

#ifndef TTYPES_H
#define TTYPES_H

#include <windows.h>

typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;

#define WSTD_DEL(x) { if ((x)) { delete (x); (x)=NULL; } }
#define WSTD_DELM(x) { if ((x)) { delete[] (x); (x)=NULL; } }

//
// String
//

class String
{
	public:
		String();
		String(char *str);
		~String();

		String& operator= (char *str);
		operator char* ();

		bool operator== (char *str);

	private:
		char *szStr;
};

#endif

Thanks in advance.
vs49688

Last edited by vs49688; Jun 1st, 2009 at 11:18 am.

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vs49688

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Jun 1st, 2009

Re: Convert LPCTSTR to std::string

Let start with..

c++ Syntax (Toggle Plain Text)
//...
md5.getHashFromString(pwd.c_str());
//...
//...
md5.getHashFromString(pwd.c_str());
//...

cikara21

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Posting Whiz

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Jun 1st, 2009

Re: Convert LPCTSTR to std::string

Try using this routine to convert from cstring to std::string using stringstream
Here is the routine

CPP Syntax (Toggle Plain Text)
#include <sstream>
#include <string>
 
using namespace std;
 
string convert(char *customString)
{
       stringstream s;
       s << customString;
       string d = s.str();
       return d;
 
}
#include <sstream>
#include <string>

using namespace std;

string convert(char *customString)
{
       stringstream s;
       s << customString;
       string d = s.str();
       return d;

}

Hope that i understood your Question.

Ahmed_I

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Jun 1st, 2009

Re: Convert Custom type 'String' to std::string

The same way std::string does it

(Toggle Plain Text)

class String
{
	public:
		String();
		String(char *str);
		~String();

		String& operator= (char *str);
		operator char* ();
        const char* c_str() {return szStr;} 
		bool operator== (char *str);

	private:
		char *szStr;
};

Ancient Dragon

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Jun 1st, 2009

Re: Convert Custom type 'String' to std::string

thanks guys. Ancient Dragon's solution solved it.

vs49688

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Jun 1st, 2009

Re: Convert Custom type 'String' to std::string

1. By the way, you must define non-trivial copy constructor and assignment operator for this class String (or declare them as private to prevent inevitable program crash if default copy constructor and/or assignment will be called).
2. If you want String to std::string conversion, define it, what's a problem?

C++ Syntax (Toggle Plain Text)
String::operator std::string() const
{
    return szStr;
}
String::operator std::string() const
{
    return szStr;
}

3. Avoid using of malloc/strdup/free stuff in C++ programs. Use new/delete operators only.

ArkM

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No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

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