{"html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fboxnos.hatenablog.com%2Fentry%2F20070908%2F1189244773\" title=\" K&amp;R\u3092\u8aad\u3082\u3046(32) \u6f14\u7fd2 2-9 - 2-10 bitcount - \u30dc\u30af\u30ce\u30b9\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","title":" K&R\u3092\u8aad\u3082\u3046(32) \u6f14\u7fd2 2-9 - 2-10 bitcount","image_url":null,"height":"190","description":"\u611f\u52d5\u3057\u305f\u3002 \u6f14\u7fd2 2-9 2\u306e\u88dc\u6570\u30b7\u30b9\u30c6\u30e0\u3067\u306f\u3001x = x & (x - 1)\u306b\u3088\u308a\u3001x\u306e\u6700\u3082\u53f3\u306e1\u30d3\u30c3\u30c8\u304c\u6d88\u3048\u308b\u3002\u4f55\u6545\u304b\u3092\u8aac\u660e\u305b\u3088\u3002\u3053\u306e\u4e8b\u5b9f\u3092\u4f7f\u3063\u3066\u3001\u3082\u3063\u3068\u65e9\u3044bitcount\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u66f8\u3051\u3002 \u8aac\u660e 01110000\u3067\u8aac\u660e\u3059\u308b\u3002x - 1\u3092\u3059\u308b\u3068\u3001 01110000 - 1 = 01101111\u4e00\u756a\u53f3\u306e1\u304c\u6d88\u3048\u3066\u3001\u53f3\u5074\u5168\u3066\u306e\u30d3\u30c3\u30c8\u304c\u7acb\u3064\u3053\u3068\u306b\u306a\u308b\u3002&\u3092\u4f7f\u3048\u3070\u30011 & 1\u4ee5\u5916\u306f\u5168\u30660\u306b\u306a\u308b\u306e\u3067\u3001x & (x - 1)\u3092\u3059\u308b\u3068\u3001 01110000 & 011011111 = 0110000x\u306e\u6700\u3082\u53f3\u306e1\u30d3\u30c3\u30c8\u304c\u6d88\u3048\u308b\u30020\u306b\u306a\u308b\u307e\u3067\u7e70\u308a\u8fd4\u305b\u3070\u3001\u30d3\u30c3\u30c8\u306e\u7acb\u3063\u305f\u6570\u304c\u308f\u304b\u308b\u3002\u7e70\u308a\u8fd4\u3057\u56de\u6570 = \u30d3\u30c3\u30c8\u306e\u2026","version":"1.0","type":"rich","url":"https://boxnos.hatenablog.com/entry/20070908/1189244773","published":"2007-09-08 18:46:13","categories":["GCC"],"blog_title":"\u30dc\u30af\u30ce\u30b9","provider_name":"Hatena Blog","blog_url":"https://boxnos.hatenablog.com/","provider_url":"https://hatena.blog","width":"100%","author_name":"tanakaBox","author_url":"https://blog.hatena.ne.jp/tanakaBox/"}