Issue while Writing\Updating .ini files using RegSetValueEx\WritePrivateProfileString

Question

I’m encountering an issue while updating an INI file. Initially, I attempted to write the value to the registry and then update the INI file using the RegSetValueEx() WinAPI. Although the function executes without returning any errors, the value is not being updated in the registry as expected.

To address this, I switched to using the WritePrivateProfileString() WinAPI. However, a similar issue occurs: the function runs without errors, but the desired output is not achieved. Notably, these issues don’t happen consistently.

Is there a fix or solution for these two problems?

Answer

I started with the Microsoft sample code and made some changes as follows -

#include  
#include 
#include  

int main()
{
    TCHAR   inBuf[80];
    HKEY   hKey1, hKey2;
    DWORD  dwDisposition;
    LONG   lRetCode;
    TCHAR   szData[] = TEXT("!USR:TestApp\Section1"); // Added ! prefix by RLWA32
    TCHAR  szPath[] = TEXT("C:\Program Files (x86)\abc\xyz\appname.ini"); //Added by RLWA32

    // Create the .ini file key. 
    lRetCode = RegCreateKeyEx(HKEY_LOCAL_MACHINE,
        TEXT("SOFTWARE\Microsoft\Windows NT\CurrentVersion\IniFileMapping\appname.ini"),
        0,
        NULL,
        REG_OPTION_NON_VOLATILE,
        KEY_WRITE,
        NULL,
        &hKey1,
        &dwDisposition);

    if (lRetCode != ERROR_SUCCESS)
    {
        printf("Error in creating appname.ini key (%d).
", lRetCode);
        return (0);
    }

    // Set a section value 
    lRetCode = RegSetValueEx(hKey1,
        TEXT("Section1"),
        0,
        REG_SZ,
        (BYTE*)szData,
        sizeof(szData));

    if (lRetCode != ERROR_SUCCESS)
    {
        printf("Error in setting Section1 value
");
        // Close the key
        lRetCode = RegCloseKey(hKey1);
        if (lRetCode != ERROR_SUCCESS)
        {
            printf("Error in RegCloseKey (%d).
", lRetCode);
            return (0);
        }
    }

    // Create an TestApp key 
    lRetCode = RegCreateKeyEx(HKEY_CURRENT_USER,
        TEXT("TestApp"),
        0,
        NULL,
        REG_OPTION_NON_VOLATILE,
        KEY_WRITE,
        NULL,
        &hKey2,
        &dwDisposition);

    if (lRetCode != ERROR_SUCCESS)
    {
        printf("Error in creating TestApp key (%d).
", lRetCode);

        // Close the key
        lRetCode = RegCloseKey(hKey2);
        if (lRetCode != ERROR_SUCCESS)
        {
            printf("Error in RegCloseKey (%d).
", lRetCode);
            return (0);
        }
    }

    // Force the system to read the mapping into shared memory 
    // so that future invocations of the application will see it 
    // without the user having to reboot the system 
    WritePrivateProfileStringW(NULL, NULL, NULL, L"appname.ini");

    // Write some added values 
    WritePrivateProfileString(TEXT("Section1"),
        TEXT("FirstKey"),
        TEXT("It all worked out OK."),
        szPath); // RLWA32 change
    WritePrivateProfileString(TEXT("Section1"),
        TEXT("SecondKey"),
        TEXT("By golly, it works!"),
        szPath); // RLWA32 change
    WritePrivateProfileString(TEXT("Section1"),
        TEXT("ThirdKey"),
        TEXT("Another test..."),
        szPath); // RLWA32 change

    // Test 
    GetPrivateProfileString(TEXT("Section1"),
        TEXT("FirstKey"),
        TEXT("Error: GPPS failed"),
        inBuf,
        80,
        szPath);
    _tprintf(TEXT("Key: %s
"), inBuf);

    // Close the keys
    lRetCode = RegCloseKey(hKey1);
    if (lRetCode != ERROR_SUCCESS)
    {
        printf("Error in RegCloseKey (%d).
", lRetCode);
        return(0);
    }

    lRetCode = RegCloseKey(hKey2);
    if (lRetCode != ERROR_SUCCESS)
    {
        printf("Error in RegCloseKey (%d).
", lRetCode);
        return(0);
    }

    return(1);
}

The path for the ini file under the Program Files(x86) folder existed before the code was run.

HKLM registry

HKLMini

HKCU registry

HKCUini

ini file created

inifilecreated

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Issue while Writing\Updating .ini files using RegSetValueEx\WritePrivateProfileString

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