[C++] copiare array di chars in un vector<char>

[gianvituzzi]

Salve,

ho il seguente problema, una funzione mi ritorna:

// Get time
char szTime[30]; getDateTime(szTime);

void getDateTime(char * szTime)
{
	time_t rawtime = time(NULL);
	struct tm timeinfo;
	gmtime_s(&timeinfo, &rawtime);
	strftime(szTime, 30, "%a, %d %b %Y %X GMT", &timeinfo);
}

ed ho un vettore di caratteri:

std::vector<char> vChar;
vChar.resize(30);

vorrei copiare da szTime a vChar con l'operatore di assegnazione = ma mi da errore...come posso risolvere il problema?

grazie!

[shodan]

Puoi fare direttamente così:

std::vector<char> vChar(&szTime[0],&szTime[30]);

oppure se è già dichiarato:

std::vector<char> vChar;
std::copy(&szTime[0],&szTime[30],std::back_inserter(vChar));

Anche se più elegante potrebbe essere:

void getDateTime(std::vector<char>& szTime)
{
	time_t rawtime = time(NULL);
	struct tm timeinfo;
	gmtime_s(&timeinfo, &rawtime);
	strftime(&szTime[0], szTime.size(), "%a, %d %b %Y %X GMT", &timeinfo);
}

std::vector<char> vChar(30);
getDateTime(vChar);

o in alternativa:

std::string getDateTime()
{
	time_t rawtime = time(NULL);
	struct tm timeinfo;
	gmtime_s(&timeinfo, &rawtime);
        std::string szTime(30,'');
	strftime(&szTime[0], szTime.size(), "%a, %d %b %Y %X GMT", &timeinfo);
        return szTime;
}

std::string vChar = getDateTime();

[antotan]

#include <vector>
#include <iostream>

using namespace std;

void print(vector<char> vc)
{
    for(vector<char>::iterator i = vc.begin(); i < vc.end(); i++) 
        cout << *i << "|";
    cout << endl;
}

int main() 
{
    char c[] = {'a', 'b', 'c'};
    int size = sizeof(c)/sizeof(c[0]);
    
    // mediante costruttore
    vector<char> vc(c, c+size);
    print(vc);
    
    vector<char> vc2;
    //mediante copy e back_inserter
    copy(c, c+size, back_inserter(vc2));
    print(vc2);
} 

edit: anticipato...

[gianvituzzi]

ho provato il codice inserito in questo programma ma non funziona:

#include <windows.h>
#include <vector>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <boost/circular_buffer.hpp>
using namespace std;
using namespace boost;

void getDateTime(char * szTime);
const int numbuff = 5;
const int buflen  = 30;

struct Buffer
{
public:
	vector<char> vChar;
	int bufferLength;
	int bytesRecorded;
	int user;
	Buffer() : bytesRecorded(0), bufferLength(0), user(0) { };
};

int main()
{
	circular_buffer<Buffer> cb(numbuff);
	circular_buffer<Buffer>::const_iterator it;

	// Insert elements
	for(int i = 0; i<10; i++)
	{
		// Get time
		char szTime[30]; getDateTime(szTime);

		// Init Buff
		Buffer buff;
		copy(&szTime[0],&szTime[30],std::back_inserter(buff.vChar));

		//buff.vChar.assign(szTime, szTime+strlen(szTime));
		buff.bufferLength  = buflen;
		buff.bytesRecorded = buflen;
		buff.user          = i;

		printf("%d, %d, %s\n", buff.user, buff.bufferLength, szTime);

		cb.push_back(buff);
	}

	// Show elements:
	for(int i = 0; i<(int)cb.size(); i++)
	{
		printf("%d, %d, %s\n", cb[i].user, cb[i].bufferLength, cb[i].vChar);
	}

	system("pause");
	return EXIT_SUCCESS;
}

// getDateTime (Fri, 10 Oct 2008 14:41:59 GMT)
void getDateTime(char * szTime)
{
	time_t rawtime = time(NULL);
	struct tm timeinfo;
	gmtime_s(&timeinfo, &rawtime);
	strftime(szTime, 30, "%a, %d %b %Y %X GMT", &timeinfo);
}

nel secondo loop for, mi ritorna <null>