不用*, /, %运算符, 写一个快速乘以7算法和一个快速除以7的算法 [有兴趣的可以试试]

[xstring]

乘7比较容易

我先给出了

unsigned int mul7 (unsigned int x)
{
return x << 3 - x;
};

大家试试div7把

[afc]

(x >> 3) + x

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[FengYuanMSFT]

You have to specify the range of x,

(x * 73 + 256) / 512 is quite close to x / 7

73 = 64 + 8 + 1

So x * 73 = (x << 8) + (x << 3) + x

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[jyc_nj]

((x-x>>3)<<3 ) | (x & 0x7);

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