Buffers Problem in Win32

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Hi,
I have win32 code for read and parsing some csv files. I am trying read files, store in buffers and next parsing and do some calculations.
Code is include Main function and some sub functions. I used Global vector buffers.

C++

#include "stdafx.h"
#include <math.h>
#include <iostream>
#include  <vector>

using namespace std;
typedef vector<char*> charA;
charA line;
vector<charA> data;
double Corr(vector<double>& Set1, vector<double>& Set2);
void Read(char *fileName);
void pars();

int _tmain(int argc, _TCHAR* argv[])
{
	

	Read("a.csv");
	cout<<data[1][1]<<"\n";
        cout<<line[1]<<"\n";
	
	line.clear();
	data.clear();

	
	return 0;
}

void Read(char *fileName){
	FILE * pFile;
		long lSize;
		char * buffer;
		size_t result;

		pFile = fopen ( fileName , "rb" );

		if (pFile==NULL) {fputs ("File error",stderr); exit (1);}

		// obtain file size:
		fseek (pFile , 0 , SEEK_END);
		lSize = ftell (pFile);
		rewind (pFile);

		// allocate memory to contain the whole file:
		buffer = (char*) malloc (sizeof(char)*lSize);
		if (buffer == NULL) {fputs ("Memory error",stderr); exit (2);}
		
		result = fread (buffer,1,lSize,pFile);
		if (result != lSize) {fputs ("Reading error",stderr); exit (3);}
			char * pch;
			pch = strtok (buffer,"\n");
		int d=0;
		while (pch != NULL) {
			line.push_back(pch);
				pch = strtok (NULL, "\n");
				
		}
		pars();
		free (buffer);
}

void pars(){
	char *pch;
	
	for(int i=0;i<line.size();i++){
		
		charA tmpArray;
	pch = strtok (line[i],",");
		while (pch != NULL) {
			 tmpArray.push_back(pch);
		pch = strtok (NULL, ",");
	}
		data.push_back(tmpArray);
	}


}

Problem is when I try read Line & data vector values in Main function not showing any values, but in Pars() & read() functions showing correct values.
Any bugs in this script?
Regards,

Posted 3-Nov-13 23:51pm

Rezame

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2 solutions

Solution 2

You are storing pointers to temporary memory into line vector while you should instead copy the content.
Why don't you define line this way:

C++

vector <string> line;

?

Posted 4-Nov-13 0:10am

CPallini

Updated 4-Nov-13 0:12am

v2

Comments

Sergey Alexandrovich Kryukov 4-Nov-13 16:04pm

5ed. It's often the good idea to get away from char*, etc...
—SA

CPallini 4-Nov-13 16:21pm

Thank you.

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Pascal-78 · Accepted Answer · 2013-11-04T00:05:00

At the end of the Read function, you free the buffer. After that (and in your main function) any reference to a pointer inside this buffer is not allowed.

You should return the buffer and free it later

C++

int _tmain(int argc, _TCHAR* argv[])
{
	
 
	char* buffer = Read("a.csv");
	cout<<data[1][1]<<"\n";
        cout<<line[1]<<"\n";
	
	line.clear();
	data.clear();
        free(buffer);
 

	
	return 0;
}

And remember, in C/C++ array are indexed starting at 0, that means line[1] is the 2nd item of array line.