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Editorial Team
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Asked: 2026-05-26T07:26:33+00:00

For example,if the integer is less than 255,than it can be restored in 1

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For example,if the integer is less than 255,than it can be restored in 1 byte,

if it’s greater than 255,it requires at lest 2 bytes.

How to write such a BYTES_REQUIRED(i) macro?

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1 Answer

  1. Editorial Team

    If you are using a C99 compiler make the cast below to (unsigned long long).
    Also you can (and should) extend the construct to 8 or 16 bytes (that’s left as an exercise)

    #include <limits.h>

#define BYTES_REQUIRED(i)                            \
           !((unsigned long)(i) >>     CHAR_BIT) ? 1 \
         : !((unsigned long)(i) >> 2 * CHAR_BIT) ? 2 \
         : !((unsigned long)(i) >> 3 * CHAR_BIT) ? 3 \
         :                                         4
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