Question

Why next code give an error? Look code and pictures. How to fix it

wchar_t *GetLine(wchar_t *fileName=L"indexing.xml", wchar_t endSymbol = '\n')
{
    FILE *file = NULL;
    int sz;
    _wfopen_s(&file, fileName, L"r");
    std::wifstream fs (file);
    int size;
    wchar_t wchr[1];
    size = 0;
    do
    {
        sz = fread(&wchr,sizeof(wchar_t),1,file);
        if(!sz)
        {
            break;
        }
        tempGetLine[size] = wchr[0];
        size++;
    }while(wchr[0] != endSymbol);
    tempGetLine[size] = '\0';
    position += (size);
    fs.close();
    return tempGetLine;
}

but this work correct

wchar_t *GetLine(wchar_t *fileName=L"indexing.xml", wchar_t endSymbol = '\n')
{
    hReadFile = CreateFileW(L"indexing.xml",GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ |FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    SetFilePointer(hReadFile,sizeof(wchar_t) * position, NULL, FILE_BEGIN);
    int size;
    wchar_t wchr[1];
    DWORD dw;
    size = 0;
    do
    {
        ReadFile(hReadFile, wchr, sizeof(wchar_t), &dw, NULL);
        if(!dw)
        {
            break;
        }
        tempGetLine[size] = wchr[0];
        size++;
    }while(wchr[0] != endSymbol);
    tempGetLine[size] = '\0';
    position += (size);
    return tempGetLine;
}

Full code

#include "stdafx.h"
#include <fstream>
#include <iostream>
#include <stdio.h>
#include <cstdio>
#include <Windows.h>
int position = 0;
wchar_t tempGetLine[500];
wchar_t *GetLine(wchar_t *fileName=L"indexing.xml", wchar_t endSymbol = '\n')
{
    FILE *file = NULL;
    int sz;
    _wfopen_s(&file, L"C:\\indexing.xml", L"r");
    std::wifstream fs (file);
    int x = GetLastError();
    fseek(file,sizeof(wchar_t) * position,SEEK_SET);
    int size;
    wchar_t wchr[1];
    size = 0;
    do
    {
        sz = fread(&wchr,sizeof(wchar_t),1,file);
        if(!sz)
        {
            break;
        }
        if(wchr[0] >= L'А')continue;            //Only for console application
        tempGetLine[size] = wchr[0];
        size++;
    }while(wchr[0] != endSymbol);
    tempGetLine[size] = '\0';
    position += (size);
    fs.close();
    return tempGetLine;
}

Answer 1

Your file has failed to open for some reason and file is NULL. Always check that files open.

Also got to wonder what you think you are doing with fs.