Class CScriptNum

src/script/script.h:188–361

};

class CScriptNum
{
/**
 * Numeric opcodes (OP_1ADD, etc) are restricted to operating on 4-byte integers.
 * The semantics are subtle, though: operands must be in the range [-2^31 +1...2^31 -1],
 * but results may overflow (and are valid as long as they are not used in a subsequent
 * numeric operation). CScriptNum enforces those semantics by storing results as
 * an int64 and allowing out-of-range values to be returned as a vector of bytes but
 * throwing an exception if arithmetic is done or the result is interpreted as an integer.
 */
public:

    explicit CScriptNum(const int64_t& n)
    {
        m_value = n;
    }

    static const size_t nDefaultMaxNumSize = 4;

    explicit CScriptNum(const std::vector<unsigned char>& vch, bool fRequireMinimal,
                        const size_t nMaxNumSize = nDefaultMaxNumSize)
    {
        if (vch.size() > nMaxNumSize) {
            throw scriptnum_error("script number overflow");
        }
        if (fRequireMinimal && vch.size() > 0) {
            // Check that the number is encoded with the minimum possible
            // number of bytes.
            //
            // If the most-significant-byte - excluding the sign bit - is zero
            // then we're not minimal. Note how this test also rejects the
            // negative-zero encoding, 0x80.
            if ((vch.back() & 0x7f) == 0) {
                // One exception: if there's more than one byte and the most
                // significant bit of the second-most-significant-byte is set
                // it would conflict with the sign bit. An example of this case
                // is +-255, which encode to 0xff00 and 0xff80 respectively.
                // (big-endian).
                if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
                    throw scriptnum_error("non-minimally encoded script number");
                }
            }
        }
        m_value = set_vch(vch);
    }

    inline bool operator==(const int64_t& rhs) const    { return m_value == rhs; }
    inline bool operator!=(const int64_t& rhs) const    { return m_value != rhs; }
    inline bool operator<=(const int64_t& rhs) const    { return m_value <= rhs; }
    inline bool operator< (const int64_t& rhs) const    { return m_value <  rhs; }
    inline bool operator>=(const int64_t& rhs) const    { return m_value >= rhs; }
    inline bool operator> (const int64_t& rhs) const    { return m_value >  rhs; }

    inline bool operator==(const CScriptNum& rhs) const { return operator==(rhs.m_value); }
    inline bool operator!=(const CScriptNum& rhs) const { return operator!=(rhs.m_value); }
    inline bool operator<=(const CScriptNum& rhs) const { return operator<=(rhs.m_value); }
    inline bool operator< (const CScriptNum& rhs) const { return operator< (rhs.m_value); }
    inline bool operator>=(const CScriptNum& rhs) const { return operator>=(rhs.m_value); }