MSVC_example_fscanf_s_and_chars_wchars, C++ (vc++)

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//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64

#include <iostream>
#include "stdio.h"
#include "wchar.h"  // provides e.g. swprintf

static void write_to_file (const char * file_name)
{
    FILE * hFile;

errno_t eError = fopen_s (&hFile, file_name, "wb");
    if (eError == 0)
    {
        int iCharsWritten = 0;

printf ("writing this data: %u %d %c %C %s %S\n", 123u, -456, 'c', L'd', "abcd", L"efgh");      // write as chars to the screen
        printf ("as chars and as wchars\n");

iCharsWritten = fprintf (hFile, "%u %d %c %C %s %S\n", 123u, -456, 'c', L'd', "abcd", L"efgh");      // write as chars
        std::cout << "Write to file as char. chars written = " << iCharsWritten << "\n";

iCharsWritten = fwprintf (hFile, L"%u %d %c %C %s %S\n", 123u, -456, L'c', 'd', L"abcd", "efgh");    // write as wchars
        std::cout << "Write to file as wchar. chars written = " << iCharsWritten << "\n";

fclose (hFile);
    }
    else
    {
        std::cout << "fopen_s for create new file: FAILED!!! error = " << eError << "\n";
    }
}

static void read_from_file (const char * file_name)
{
    FILE * hFile;

errno_t eError = fopen_s (&hFile, file_name, "rb");
    if (eError == 0)
    {
        unsigned int u = 0u;
        signed int s = 0;
        char c = '0';
        wchar_t d = L'0';

char ac[64] = "0";
        wchar_t aw[64] = L"0";
            
        int iResult = 0;
            
        std::cout << "_countof(ac) = " << _countof(ac) << "\n"; /* 64 */
        std::cout << "  sizeof(ac) = " <<   sizeof(ac) << "\n"; /* 64 */
        std::cout << "_countof(aw) = " << _countof(aw) << "\n"; /* 64 */
        std::cout << "  sizeof(aw) = " <<   sizeof(aw) << "\n"; /* 128 */

/* char */
        std::cout << "char:\n";

iResult = fscanf_s (hFile, "%u", &u);
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << u << "\n";

iResult = fscanf_s (hFile, "%d", &s);
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << s << "\n";

iResult = fscanf_s (hFile, " %c", &c);  /* please note the leading space in the format string */
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << c << "\n";

iResult = fscanf_s (hFile, " %c", &c);  /* please note the leading space in the format string */
        d = btowc (c); /* the value in the file is stored using only chars, not wchars! */
        std::wcout << L"Read from file. fscanf_s result = " << iResult << L"; retrived value: " << d << L"\n";  /* wchars must be printed using wcout */

iResult = fscanf_s (hFile, "%s", ac, _countof(ac)); /* without the count we will likely see a segementation fault inside the function call */
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << ac << "\n";

iResult = fscanf_s (hFile, "%s", ac, _countof(ac)); /* without the count we will likely see a segementation fault inside the function call */
        swprintf_s (aw, L"%S", ac); /* the value in the file is stored using only chars, not wchars! */
        std::wcout << L"Read from file. fscanf_s result = " << iResult << L"; retrived value: " << ac << L"\n";  /* wchars must be printed using wcout */

/* wchar */
        u = 0u;
        s = 0;
        c = '0';
        d = L'0';

strcpy_s (ac, "0");
        wcscpy_s (aw, L"0");

std::cout << "wchar:\n";

#if 0 /* TODO */
        iResult = fwscanf_s (hFile, L"%u", &u);
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << u << "\n";

iResult = fwscanf_s (hFile, L"%d", &s);
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << s << "\n";

iResult = fwscanf_s (hFile, L" %c", &c);  /* please note the leading space in the format string */
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << c << "\n";

iResult = fwscanf_s (hFile, " %C", &d);  /* please note the leading space in the format string */
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << d << "\n";

iResult = fwscanf_s (hFile, L"%S", ac, _countof(ac)); /* without the count we will likely see a segementation fault inside the function call */
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << ac << "\n";

iResult = fwscanf_s (hFile, L"%s", aw, _countof(aw)); /* without the count we will likely see a segementation fault inside the function call */ /* the value in the file is stored using only chars, not wchars! */
        std::cout << "Read from file. fscanf_s result = " << iResult << "; retrived value: " << aw << "\n";
#endif

fclose (hFile);
    }
    else
    {
        std::cout << "fopen_s for read from file: FAILED!!! error = " << eError << "\n";
    }
}

int main(int argc, char * argv[])
{
    std::cout << "Hello, world!\n";

const char file_name[] = "helper.txt";

write_to_file (file_name);

read_from_file (file_name);

return 0;
}

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Compilation time: 1,83 sec, absolute running time: 0,21 sec, absolute service time: 2,05 sec