> In article
> <f3dab86c-491a-441c-a0ed-7acb69aec
...@d21g2000yqn.googlegroups.com>,
> Francesco <xtrigger...@gmail.com> wrote:
> > Hi to all,
> > would any of you gentlemen please comment on the reinterpret_casts in
> > the code below?
> > Do you think they're ok or not? Any reference to the standard would be
> > greatly appreciated.
> > Thank in advance,
> > FB
> > //CODE
> > #include <iostream>
> > #include <iomanip>
> > typedef float ( * tMtx )[ 4 ];
> > void Fill( tMtx inMtx )
> > {
> > for( int c = 0; c < 16; ++c )
> > inMtx[ c / 4 ][ c % 4 ] = c;
> > }
> > void Print( tMtx inMtx )
> > {
> > std::cout << "n->" << inMtx << std::endl;
> > for( int c1 = 0; c1 < 4; ++c1 )
> > {
> > for( int c2 = 0; c2 < 4; ++c2 )
> > std::cout << std::setw( 5 ) << inMtx[ c1 ][ c2 ];
> > std::cout << std::endl;
> > }
> > std::cout << std::endl;
> > }
> > int main()
> > {
> > float mtx1[ 16 ] = { 0 };
> > float mtx2[ 4 ][ 4 ];
> > float * mtx3 = new float[ 16 ];
> > float * mtx4 = reinterpret_cast< float * >( new float[ 4 ][ 4 ] );
> > // are these casts OK?
> > Fill( reinterpret_cast< tMtx >( mtx1 ) );
> > Fill( mtx2 );
> > Fill( reinterpret_cast< tMtx >( mtx3 ) );
> > Fill( reinterpret_cast< tMtx >( mtx4 ) );
> > Print( reinterpret_cast< tMtx >( mtx1 ) );
> > Print( mtx2 );
> > Print( reinterpret_cast< tMtx >( mtx3 ) );
> > Print( reinterpret_cast< tMtx >( mtx4 ) );
> > delete[] mtx3;
> > delete[] mtx4;
> > std::cin.get();
> > }
> > //ENDCODE
> It's doable, but I would do it differently:
> // begin code
> typedef float m16[16];
> typedef float m44[4][4];
> void Fill(m44& v) {
> for(int c = 0; c < 16; ++c)
> v[c / 4][c % 4] = c;
> }
> void Fill(m16& v) {
> Fill(reinterpret_cast<m44&>(v));
> }
> void Print(const m44& v) {
> cout << "n->" << v << endl;
> for (int c1 = 0; c1 < 4; ++c1) {
> for (int c2 = 0; c2 < 4; ++c2)
> cout << setw(5) << v[c1][c2];
> cout << endl;
> }
> cout << endl;
> }
> void Print(const m16& v) {
> Print(reinterpret_cast<const m44&>(v));
> }
> int main()
> {
> float mtx1[16] = { 0 };
> float mtx2[4][4];
> Fill(mtx1);
> Fill(mtx2);
> Print(mtx1);
> Print(mtx2);
> cin.get();}
> // end code
> Even if you are stuck with the Fill and Print you have, I would still
> wrap the casts in functions that take the appropriate types. That way
> you don't have (1) reinterpret_cast all over your code and (2) it is
> less likely that someone will reinterpret_cast the wrong sort of
> variable.- Nascondi testo citato
> - Mostra testo citato -
|
