String in der Datei ersetzen...

[client]

Hallo,
wie kann ich den ein bestimmtes String in einer txt-Datei durch ein anderes ersetzen???
z.b:
asd sdf jlk
(sdf durch qwe)

Ergebnis:
asd qwe jlk

[the_alien]

Datei einlesen, String finden, String ersetzen, geänderten String in Datei schreiben.

[client]

Also doch die komplette Datei einlesen...

[cplusplus.]

hi!
habs mal versucht schnell zu coden;-) jedoch schreibt er bei mir nichts in die datei...dh.: er überschreibt die alte datei und die bleibt dann leer...hmm weiss jetzt auch nicht warum...?

cu

#include <algorithm>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
#include <map>
using namespace std;

#define STR(x) # x
#define SSTR(x) STR(x)

class LogBook
{
private:
	std::string filename;
	std::string search_str;
	std::string replace_str;
	std::string txt_str;
	fstream m_stream;

	void openfile(bool read_write)
	{
		try
		{
			int pos = filename.find(".");
			string s1 = filename.substr(pos, filename.length());
			if(s1 != ".txt")
				throw runtime_error("::File open failed, unsupported file format! " __FILE__ " " SSTR(__LINE__));

			// Datei oeffnen
			if(read_write == 0) {
				m_stream.open(filename.c_str(), ios::in);
			}
			else {
				m_stream.open(filename.c_str(), ios::out);
			}

			if (!m_stream) {
				throw runtime_error("::File open failed! " __FILE__ " " SSTR(__LINE__));
			}
		}
	    catch(...)
	    {	
			m_stream.close();

		    throw;
	    }
	}

	void replace_all(string &s, const char *from, const char *to)
	{
		unsigned pos = 0, len = strlen( from );

		while ((pos = s.find( from, pos )) != s.npos)
		{
			s.replace( pos, len, to );
		}
	}

	void read()
	{
		std::string str_read;

		while (m_stream.good())
		{
			str_read = "";
			getline(m_stream, str_read);

			replace_all(str_read, search_str.c_str(), replace_str.c_str());
		}

		txt_str += str_read;
	}

	void write()
	{
		m_stream << txt_str << endl;
		cout << txt_str << endl;
	}

	void closefile()
	{
		m_stream.close();
	}

public:
	LogBook(const std::string &search_str_, const std::string &replace_str_, const std::string &filename_): search_str(search_str_), replace_str(replace_str_), filename(filename_) {}

	void replace()
	{
		openfile(false);
		read();
		closefile();
		openfile(true);
		write();
		closefile();
	}
};

template<class T>
void WaitForReturn(T& stream)
{
	stream.clear();
	stream.ignore(stream.rdbuf()->in_avail());
	stream.get();
}

int main()
{
	LogBook book("hallo", "sers", "File.txt");
	book.replace();

	WaitForReturn(cin);
	return 0;
}

[cplusplus.]

hi!
so nun fehler gefunden, problem war: ich hatte den fstream nicht gelöscht vor dem öffnen...m_stream.clear();
LogBook book("hallo", "sers", "File.txt");
in der datei File.txt werden alle hallo durch sers ersetzt...
code ist sicher nicht der schöneste...soll nur mal zeigen wie es gehen kann;-)

cu

#include <fstream>
#include <iostream>
#include <string>
using namespace std;

#define STR(x) # x
#define SSTR(x) STR(x)

class LogBook
{
private:
	std::string filename;
	std::string search_str;
	std::string replace_str;
	std::string txt_str;
	fstream m_stream;

	void openfile(bool read_write)
	{
		try
		{
			int pos = filename.find(".");
			string s1 = filename.substr(pos, filename.length());
			if(s1 != ".txt")
				throw runtime_error("::File open failed, unsupported file format! " __FILE__ " " SSTR(__LINE__));

			m_stream.clear();

			// Datei oeffnen
			if(read_write == 0) {
				m_stream.open(filename.c_str(), ios::in);
			}
			else {
				m_stream.open(filename.c_str(), ios::out);
			}

			if (!m_stream) {
				throw runtime_error("::File open failed! " __FILE__ " " SSTR(__LINE__));
			}
		}
	    catch(...)
	    {	
			m_stream.close();

		    throw;
	    }
	}

	void replace_all(std::string &s, const char *from, const char *to)
	{
		unsigned pos = 0, len = strlen( from );

		while ((pos = s.find( from, pos )) != s.npos)
		{
			s.replace( pos, len, to );
		}
	}

	void read()
	{
		std::string str_read;

		while (m_stream.good())
		{
			str_read = "";
			getline(m_stream, str_read);	
			replace_all(str_read, search_str.c_str(), replace_str.c_str());
			txt_str += str_read;
			txt_str += '\n';
		}

		if(!txt_str.empty() && txt_str[txt_str.length()-1]=='\n') { txt_str.erase(txt_str.end()-1); }
	}

	void write()
	{
		m_stream << txt_str;
		cout << txt_str << endl;
	}

	void closefile()
	{
		m_stream.close();
	}

public:
	LogBook(const std::string &search_str_, const std::string &replace_str_, const std::string &filename_): search_str(search_str_), replace_str(replace_str_), filename(filename_) {}

	void replace()
	{
		openfile(false);
		read();
		closefile();
		openfile(true);
		write();
		closefile();
	}
};

template<class T>
void WaitForReturn(T& stream)
{
	stream.clear();
	stream.ignore(stream.rdbuf()->in_avail());
	stream.get();
}

int main()
{
	LogBook book("hallo", "sers", "File.txt");
	book.replace();

	WaitForReturn(cin);
	return 0;
}