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Flip the bit at poistion n in an int variable

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• Flipping a bit
  • Recall: how to flip a bit

    Bit position: 6543210 Starting bit pattern: ..............x............... Bit mask: 000000000000001000000000000000 ----------------------------------------- XOR ..............1............... (Bit dnoted by . will remain unchaned)

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• Making the bit mask
  • The bit mask 00000000000010000000000000... canbe made with the following operation:

    i positions <--------------> 1 << i = 000000..1000000000000000

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• C statement to flip bit position i in an int variable
  • C code:

    int x; int i; x = x ^ (1 << i ); // Flip bit position i in x

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• Macro definition for flipbit operation
  • C macro to flip the bit at position i in a variable x:

    #define FLIPBIT( x, i ) ( x ^= (1 << i) )