Re^8: Odometer pattern iterator (in C).

I attempted to adapt your Perl to C, but I made a mistake somewhere. I don't know if you can see the problem, but I can't and I need to move on:

U8 *firstIdx(  U8 N, U8 M ) {
    U32 i;
    U8 *a = malloc( M );
    for( i = N - M; i < N; ++i ) a[ i - M + 1 ] = i;
    return a;
}

U8 *nextIdx( U8 N, U8 M, U8 *idx ) {
    U32 i = M - 1, j;

    if( idx[ i ] == i ) return NULL;

    while( i > 0 && idx[ i ] - idx[ i - 1 ] == 1 ) i--;

    --idx[ i ];

    for( j = i+1; j < M; ++j ) idx[ i ] += N - idx[ M - j + i ];

    return idx;
}
[download]

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". I'm with torvalds on this

In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked

Comment on Re^8: Odometer pattern iterator (in C). Download Code

Replies are listed 'Best First'.
Re^9: Odometer pattern iterator (in C). by hdb (Monsignor) on May 29, 2015 at 15:12 UTC
You cannot do this inplace: `for( j = i+1; j < M; ++j ) idx[ i ] += N - idx[ M - j + i ];` [download] as you are overwriting values that are still needed. This corresponds to the "reversing" the string part of the regex. In addition, you misread the formula, there is no `+=` involved.	[reply] [d/l] [select]