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  • 运算符的优先级级别搞错的痛苦代价

    PrecedenceOperatorDescriptionAssociativity
    1 :: Scope resolution Left-to-right
    2 ++   -- Suffix/postfix increment and decrement
    () Function call
    [] Array subscripting
    . Element selection by reference
    -> Element selection through pointer
    3 ++   -- Prefix increment and decrement Right-to-left
    +    Unary plus and minus
    !   ~ Logical NOT and bitwise NOT
    (type) Type cast
    * Indirection (dereference)
    & Address-of
    sizeof Size-of
    newnew[] Dynamic memory allocation
    deletedelete[] Dynamic memory deallocation
    4 .*   ->* Pointer to member Left-to-right
    5 *   /   % Multiplication, division, and remainder
    6 +    Addition and subtraction
    7 <<   >> Bitwise left shift and right shift
    8 <   <= For relational operators < and ≤ respectively
    >   >= For relational operators > and ≥ respectively
    9 ==   != For relational = and ≠ respectively
    10 & Bitwise AND
    11 ^ Bitwise XOR (exclusive or)
    12 | Bitwise OR (inclusive or)
    13 && Logical AND
    14 || Logical OR
    15 ?: Ternary conditional Right-to-left
    = Direct assignment (provided by default for C++ classes)
    +=   −= Assignment by sum and difference
    *=   /=   %= Assignment by product, quotient, and remainder
    <<=   >>= Assignment by bitwise left shift and right shift
    &=   ^=   |= Assignment by bitwise AND, XOR, and OR
    16 throw Throw operator (for exceptions)
    17 , Comma Left-to-right
         
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           

    自以为 << 的优先级高于 + ,导致错误的结果!

    short c = (short)( (high << 8) + low);
    short d = (short)( high << 8 + low);
    short f = (short)( high << (8 + low));
    // d与f结果一致,
    

      

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  • 原文地址:https://www.cnblogs.com/fornever/p/3402313.html
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