error: acces violation

poema (1)

Guys,

I've a little problem with a little program and I can't figure out what the problem is and how to solve it.
Purpose of the program:
open a .csv file
read a line
split the string (delimiter = ; ) and store the substrings.

Sounds easy, however: it won't run, it doesn't give errors and while debugging it says:

Unhandled exception at 0x102aece9 in LetsTest.exe: 0xC0000005: Access violation writing location 0x00000000.

when jumping to strcpy().

Who can help me? It's a subfunction of a bigger project with a deadline way too soon!
Thank you very much,

poema.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

int main()
{
	int nrOfTypes=3;
	char* reads[3];
	char delims[]=";";
	string csvfile="sensorData.csv";
	
	//open&read file
	ifstream myfile;
	myfile.open(csvfile.c_str());
	char* id=NULL;
	char* time=NULL;
	char* s=NULL;
	char* copy=NULL;
	string line;
	while (!myfile.eof())
	{
		getline( myfile,line);
		strcpy( copy,  line.c_str()); 
		id=strtok(copy,delims);
		printf( "result %s \n", id);
		time=strtok(NULL,delims);
		printf( "result %s \n", time);
		for(int i=0;i<nrOfTypes;i++)
		{
			reads[i]=strtok(NULL,delims);
			printf( "result %s \n", reads[i]);
		}
	}
	myfile.close();
	return 0;
}

ps: the .csv file is filled with this kind of strings: "1;18/03/2008 11:55;20;-95;498"

guestgulkan (150)

Line 14 and 19 are the problem(s).
in line 14 -

1 2

 char* copy=NULL;

you have initialised copy to be a NULL (0) pointer and in line
19 you try copying to it !!!! hence the access violation.

you don't need the strcpy function in line 19 because line.c_str returns a char*.
So change line 19 to


 copy= (char*)line.c_str();

.
You may need the cast because line.c_str returns a


const

pointer .

I used a 'C' style cast, but the c++ way


copy= const_cast <char*>line.c_str();

maybe the more official way to do it.

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