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random

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random, srandom, initstate, setstate - Íð¿ô¤òÀ¸À®¤¹¤ë´Ø¿ô

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#include <stdlib.h>



long int random(void);




void srandom(unsigned int seed);




char *initstate(unsigned int seed, char *state, size_t n);




char *setstate(char *state);

ÀâÌÀ

random() ´Ø¿ô¤Ï¡¢ÈóÀþ·Á²ÃË¡¥Õ¥£¡¼¥É¥Ð¥Ã¥¯¤òÍѤ¤¤¿Íð¿ôÀ¸À®´Ø¿ô¤Ç¤¢¤ë¡£ ¤³¤Î´Ø¿ô¤Ï¡¢0 ¤«¤é RAND_MAX ¤Þ¤Ç¤Îµ¿»÷Íð¿ô¤òÊÖ¤¹¡£ ¤½¤Î¤¿¤á¤Ë 31 ¸Ä¤Î¥í¥ó¥°À°¿ô¤«¤é¤Ê¤ë¥Ç¥Õ¥©¥ë¥È¤Îɽ¤ò»ÈÍѤ¹¤ë¡£ ¤³¤ÎÍð¿ô¤òÀ¸À®¤¹¤ë´Ø¿ô¤Î¼þ´ü¤Ï¤È¤Æ¤âŤ¯¡¢¤ª¤è¤½ 16*((2**31)-1) ¤Ç¤¢¤ë¡£

srandom() ´Ø¿ô¤Ï¡¢ random() ¤ÇÊÖ¤µ¤ì¤ëµ¿»÷Íð¿ôÀ°¿ô·ÏÎó¤Î¼ï¤òÀßÄꤹ¤ë¡£ ¤½¤Î¤¿¤á¤Ë¤Ï¿·¤·¤¤¼ï¤ò°ú¿ô¤Ë¤·¤Æ srandom() ¤ò¸Æ¤Ù¤Ð¤è¤¤¡£ random() ¤ÇÀ¸À®¤µ¤ì¤ë·ÏÎó¤Ï¡¢ °ú¿ô¤ËƱ¤¸¼ï¤ÎÃͤòÍѤ¤¤Æ srandom() ¤ò¸Æ¤Ö¤³¤È¤ÇºÆ¸½²Äǽ¤Ç¤¢¤ë¡£ ¼ï¤ÎÃͤ¬Í¿¤¨¤é¤ì¤Ê¤¤¾ì¹ç¤Ë¤Ï random() ´Ø¿ô¤Ï¡¢¼«Æ°Åª¤Ë 1 ¤ò¼ï¤ËÀßÄꤹ¤ë¡£

initstate() ´Ø¿ô¤Ï¡¢ random() ¤Ç»ÈÍѤµ¤ì¤ë¾õÂÖÇÛÎó state ¤ò½é´ü²½¤¹¤ë¡£ initstate() ¤Ç¤Ï¡¢¾õÂÖÇÛÎó¤ÎÂ礭¤µ n ¤Ï »ÈÍѤ¹¤ë´Ø¿ô¤ÎÍð¿ôÀ¸À®¤ÎÀ­Ç½¤ÎÄøÅÙ¤ò·èÄꤹ¤ë¤¿¤á¤Ë»ÈÍѤµ¤ì¤ë --- ¾õÂÖÇÛÎó¤¬Â礭¤¤Äø¡¢Íð¿ô¤ÎÀ­Ç½¤Ï¤è¤¯¤Ê¤ë¡£ seed ¤Ï½é´ü²½¤Î¤¿¤á¤Î¼ï¤Ç¤¢¤ë¡£ ¤³¤ì¤ÏÍð¿ô·ÏÎó¤Î³«»Ï°ÌÃÖ¤ò·èÄꤹ¤ë¤â¤Î¤Ç¤¢¤ê¡¢ ¤³¤ÎÃͤò»ØÄꤹ¤ë¤³¤È¤ÇƱ°ì¤Î³«»Ï°ÌÃÖ¤«¤éÍð¿ô¤ÎÀ¸À®¤ò ºÆ³«¤¹¤ë¤³¤È¤¬¤Ç¤­¤ë¡£

setstate() ´Ø¿ô¤Ï¡¢ random() ¤Ç»ÈÍѤµ¤ì¤ë¾õÂÖÇÛÎó¤òÊѹ¹¤¹¤ë¡£ ¾õÂÖÇÛÎó state ¤Ï¡¢ initstate() ¤Þ¤¿¤Ï setstate() ¤¬ ¼¡¤Ë¸Æ¤Ó½Ð¤µ¤ì¤ë¤Þ¤Ç¡¢Íð¿ô¤ÎÀ¸À®¤Ë»ÈÍѤµ¤ì¤ë¡£ state ¤Ï initstate() ¤òÍѤ¤¤ÆºÇ½é¤Ë½é´ü²½¤µ¤ì¤Æ¤¤¤ë¤«¡¢ °ÊÁ°¤Ë¸Æ¤Ó½Ð¤·¤¿ setstate() ¤Î·ë²Ì¤Ç¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£

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random() ´Ø¿ô¤Ï0¤ÈRAND_MAX¤Î´Ö¤ÎÃͤòÊÖ¤¹¡£ srandom() ´Ø¿ô¤ÏÃͤòÊÖ¤µ¤Ê¤¤¡£ initstate() ´Ø¿ô¤È setstate() ´Ø¿ô¤Ï ľÁ°¤Î¾õÂÖÇÛÎó¤Ø¤Î¥Ý¥¤¥ó¥¿¤Þ¤¿¤Ï NULL ¤òÊÖ¤¹¡£

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initstate() ¤Ç8¥Ð¥¤¥È¤è¤ê¤â¾®¤µ¤¤¾õÂÖÇÛÎó¤ò»ØÄꤷ¤¿¡£

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4.3BSD, POSIX.1-2001.

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rand(3), srand(3)