C / C++ / MFC

fx9200 wrote:

the memory space was not kept after function return;

fx9200 wrote:

how to pass reference(pointer) by reference ?

please give example

fx9200 wrote:

yes

so ?

void AddOne( int nTheVariable )
{
    nTheVariable = nTheVariable + 1;
}

void main()
{
    int nMyValue = 0;
    printf( "The value is %d.\n", nMyValue ); // Prints "The value is 0."
    AddOne( nMyValue );
    printf( "The value is %d.\n", nMyValue ); // Also prints "The value is 0."
}

void AddOne( int* pnTheVariable )
{
    // Here we've got a copy of the address of the variable so
    // we can modify it at its original location 
    *pnTheVariable = *pnTheVariable + 1;
}

void main()
{
    int nMyValue = 0;
    printf( "The value is %d.\n", nMyValue ); // Prints "The value is 0."
    AddOne( &nMyValue ); // Pass a copy of the address of nMyValue
    printf( "The value is %d.\n", nMyValue ); // Prints "The value is 1."
}

void Allocate( int** ppnTheMemory )
{
    *ppTheMemory = (int*)malloc( 3 * sizeof( int ) );
}

void main()
{
    int* pnMyValues = NULL;
    Allocate( &pnMyValue ); // Pass the address of the pointer
    if( pnMyValues )
    {
        free( pnMyValues );
        pnMyValues = NULL;
    }
}

void fill( struct mystruct** ppTheStruct );

void main()
{
    struct mystruct* pMyStruct = NULL;
    fill( &pMyStruct ); // Pass the address of the pointer
    ...
    if( pMyStruct )
    {
        free( pMyStruct ); // Don't forget to return what you've borrowed ;-)
        pMyStruct = NULL; // Not necessary but considered good practice
    }
}

void fill( struct mystruct** ppMyStruct )
{
    *ppMyStruct = (struct mystruct*)malloc( sizeof( struct mystruct ) );
    ....
}

jeepoo wrote:

i am having an exe in my drive i have to call it from my mfc code. how to do this

WhiteSky wrote:

I dont know why you get 2 votes(1.8) I give you 5;)

WhiteSky wrote:

You are optimistic

WhiteSky wrote:

I think optimistic is better than pessimistic it sends affirmative signal to man,right;)