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vanhoosr
10y

When I see a coworker do this:

if( recValues[0] == '0' )
{
recValues[0] = '1';
}
else if( recValues[0] == '1' )
{
recValues[0] = '0';
}

I replace it with this:

recValues[0] ^= 0x1;

Note: The recValues[0] is guaranteed to contain only '0' or '1'

undefined
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  • 4
    10y
    Or you can write:
    recValues[0]=(recValues[0]+1)%2;
  • 8
    10y
    what kind of devil language is this
  • 14
    10y
    If 0 and 1 are considered booleans in that language you could just negate them:

    recvalues[0] = ! recvalues[0];
  • 2
    10y
    recvalues[0] = Math.Abs(recvalues[0]-1);
    Math is everything
  • 2
    10y
    @matyjb recvalues[0] = 1 - recvalues[0]. That's how I'm used to see it anyway :)
  • 0
    10y
    I could agree with you, but typing 0x1 instead of just 1 (recValues ^= 1) is just to make it look unreadable on purpose, isn't it?
  • 0
    10y
    @Huuugo am I the only one that thinks this is a good answer?
  • 7
    10y
    Oh wait. It just hit me. The array contains chars! WTF.
    '0' ! = 0
    None of the answers above are correct (including mine), are they?

    If so,
    x = x == '0' ? '1' : '0'
    Would be the easiest
  • 1
    10y
    recValues [0] = (recValues [0]==='0') ? '1' : '0';
  • 2
    10y
    @Joserc87 More out of habit. I'm a Computer Engineer, so I use hex a lot.
    I also use bitwise operators a lot, so that's where the solution comes from.
    In the actual implementation I wrapped 0x1 in a macro with an easy-to-read name so nobody wonders what the 0x1 does.
  • 0
    10y
    I mean, yes: Using bitwise operators IS a little bit more unreadable. But the speedup in compiled code is significant -- especially if it gets executed inside a loop. Usually when I use bitwise operators I put a comment in.
  • 0
    10y
    If the performance matters then yes, totally, get rid of the conditional jumps!
    But then again, if it really matters and it's in an algorithm you can bundle that array into a byte or a word? I'm curious about what this actually does
  • 1
    10y
    @Joserc87 Switches a '0' to a '1' and vice versa.
    The actual code was part of a file I/O program. The actual program is meant to toggle a GPIO pin, on or off.
    So the program has to: Read the bit, change it, then write it back.
  • 2
    10y
    rectValue[0]= 1- rectValue[0]
    Simple enough
  • 2
    10y
    At first I really thought the program was wrong because of the char to int jump.. but it's right. I'm an amateur embedded systems engineer from the CS world. It took me a bit to realize you are just flipping the last bit of the character. Duh!
  • 2
    10y
    Why not x = !x ?

    Or, funnier:

    x = |x - 1|

    x = cos(M_PI_2 * x)

    Ok that's it :P
  • 0
    10y
    I compiled the top-suggested alternative solutions. The conditional assignment is only a little bit faster than if/else. Two assembly instructions fewer, to be exact.
    The bitwise operation was 30% faster than the conditional assignment.
  • 0
    10y
    Why does the bitwise operator work there? The values are char, so just arbitrary ASCII bit patterns... Seems like a coincidence.
  • 0
    10y
    '0' is 0x30 and '1' is 0x31 in ASCII
    The ASCII characters were arranged so you can do things like iterate through them in ascending order. Other cool things too:
    'a' is 0x61
    'A' is 0x41
    so to convert between lower case and upper case just add or subtract 0x20.
  • 0
    10y
    in binary:
    '1' is 0011 0000
    '0' is 0011 0001

    so Exclusive-Or either with 1 flips bit 0 and only bit zero
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