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Muzaffar Mahkamov · Guest

Hi,

I'm trying to compile Botan encryption library in Borland C++ Builder 6.
Mostly I have problems with functions that increment pointers to
const arrays.

void MD2::add_data(const byte input[], u32bit length)
{
buffer.copy(position, input, length);
if(position + length >= HASH_BLOCK_SIZE)
{
hash(buffer.begin());
input += (HASH_BLOCK_SIZE - position); // the compilation fails
here, cannot modify const object

length -= (HASH_BLOCK_SIZE - position);
while(length >= HASH_BLOCK_SIZE)
{
hash(input);
input += HASH_BLOCK_SIZE; // also fails here
length -= HASH_BLOCK_SIZE;
}
buffer.copy(input, length);
position = 0;
}
position += length;
}

Microsoft Visual C++ 7.0 compiler does not fail. I think, the Borland
compiler shouldn't too, because i'm not modifying the array contents,
i'm modifying the pointer (which is not const).

The only quick solution came to my mind was removing the "const"
modifier using the const_cast. Removing the "const" modifier from all
the functions would take much longer time.

void MD2::add_data(const byte input2[], u32bit length)
{
byte* input = const_cast<byte*>(input2);

buffer.copy(position, input, length);
if(position + length >= HASH_BLOCK_SIZE)
{
hash(buffer.begin());
input += (HASH_BLOCK_SIZE - position);
length -= (HASH_BLOCK_SIZE - position);
while(length >= HASH_BLOCK_SIZE)
{
hash(input);
input += HASH_BLOCK_SIZE;
length -= HASH_BLOCK_SIZE;
}
buffer.copy(input, length);
position = 0;
}
position += length;
}

Is there a more elegant (and correct) solution to this problem? What do
the standards say about this issue?

Thanks in advance,
Muzaffar

Chris Uzdavinis (TeamB) · Guest

Muzaffar Mahkamov <muzaffar (AT) design (DOT) uz> writes:

Alex Bakaev [TeamB] · Guest

Muzaffar Mahkamov wrote:

Muzaffar Mahkamov · Guest

Chris Uzdavinis (TeamB) wrote:

Muzaffar Mahkamov · Guest

Chris Uzdavinis (TeamB) wrote: