真正随机数的产生
今天小明和小红玩游戏，决定如果谁要是输了就要受到惩罚。可是怎么惩罚呢，惩罚的方式小明找了找，找到了这么几条：
1,自己主动激情舌吻10s以上
2,上下对卧,自己做10个俯卧撑
3,脱内衣一件
4,给对方按摩5分钟
5,今天所有的衣服归你洗
6,对视,将对方手捧在脸旁,说五次:我爱你,我要嫁给你.
实行哪一条呢？ 问题出来了。这个时候小明用有道词典翻译了上面的句子，写出了一个程序用来决定用哪个惩罚。
程序目的：产生随机数 1-6
执行方法：L 开始 G 结束运行，显示执行结果。
1 #include "stdio.h" 2 #include "stdlib.h" 3 #include "conio.h" 4
5 6 #define TOTAL 6 7 8 #define TURE 1 9 #define FAULT 0 10 11 int main () 12 { 13 char *rules [6] = {"1 : initiative, tongue kiss more than 10s passionately.", 14 "2 : To lie, at the top, to do 10 pushups.", 15 "3 : To lie on both sides, in upper part, to do 10 pushups.", 16 "4 : Take off a piece of underwear.", 17 "5 : You have to wash all of the clothes.", 18 "6 : In the eye, take each other next to hand on the face, said five times: I love you, I want to marry you." 19 }; 20 21 char in_number ; 22 char in_key; 23 int i,j; 24 25 printf ("please enter 'L' to start the lover game : "); 26 scanf("%c" , &in_number); 27 while (in_number!='L') 28 { 29 printf (" input error !\n "); 30 printf ("please input 'L' to start the game "); 31 fflush(stdin); 32 scanf("%c" , &in_number); 33 } 34 35 printf ("please input 'G' to end "); 36 while (in_key != 'G') 37 { 38 i = (int)rand(); 39 i = i % (TOTAL); 40 scanf("%c" , &in_key); 41 if(in_key == 'G') 42 { 43 printf (" Accept the punishment! ! ! \n"); 44 printf ("THE NUMBER IS %d \n ",(i+1)); 45 printf ("%s\n\n\n", *(rules + i)); 46 } 47 } 48 system ("pause"); 49 }
聪明的小红发现每次如果正确输入L G 输出的结果一直都是 6 。这个时候小红就抗议了，说小明的程序有问题，这六个数字不是随机的。是小明事先安排好的。小明有理说不清啊，只能继续研究。后来查阅到。C语言中 rand（）随机函数是伪随机。不是真正的随机。
既然是伪随机，那就要和自己的GF解释清楚啊，解释清楚了还要解决。于是在 37 38 行之间加上语句 ：
srand((unsigned)time(NULL));
头文件 #include <time.h>
作用就是
首先给srand()提供一个种子，它是一个unsigned int类型，其取值范围从0~65535
然后调用rand()，它会根据提供给srand()的种子值返回一个随机数(在0到32767之间)
根据需要多次调用rand()，从而不间断地得到新的随机数；
无论什么时候，都可以给srand()提供一个新的种子，从而进一步“随机化”rand()的输出结果
最终结果：
1 //date : 13/11/25 2 //designer :pengxiaoen 3 // function : lover game 4 5 #include "stdio.h" 6 #include "stdlib.h" 7 #include "conio.h" 8 #include <time.h> 9 10 #define TOTAL 6UL 11 #define TURE 1 12 #define FAULT 0 13 14 int main () 15 { 16 char *rules [6] = {"1 : initiative, tongue kiss more than 10s passionately.", 17 "2 : To lie, at the top, to do 10 pushups.", 18 "3 : To lie on both sides, in upper part, to do 10 pushups.", 19 "4 : Take off a piece of underwear.", 20 "5 : You have to wash all of the clothes.", 21 "6 : In the eye, take each other next to hand on the face, said five times: I love you, I want to marry you." 22 }; 23 char in_number ; 24 char in_key; 25 int i,j; 26 27 printf ("please enter 'L' to start the lover game : "); 28 scanf("%c" , &in_number); 29 while (in_number!='L') 30 { 31 printf (" input error !\n "); 32 printf ("please input 'L' to start the game "); 33 fflush(stdin); 34 scanf("%c" , &in_number); 35 } 36 37 printf ("please input 'G' to end : "); 38 while (in_key != 'G') 39 { 40 srand((unsigned)time(NULL)); 41 i = (int)rand(); 42 i = i % (TOTAL); 43 scanf("%c" , &in_key); 44 if(in_key == 'G') 45 { 46 printf ("\n\n\n\n\n Accept the punishment! ! ! \n"); 47 printf (" THE NUMBER IS %d\n ",(i+1)); 48 printf (" %s\n\n\n\n\n", *(rules + i)); 49 } 50 } 51 system ("pause"); 52 }
OK 搞定，给了时间种子，随机数每次执行都不一样了。基本上实现了随机性。
总结：泡妞也要用头脑
