awk的随机数是怎么生成的？

bulletmarquis

1. awk 'BEGIN{print rand()}'
   
2. 0.237788
   
3. awk 'BEGIN{print rand()}'
   
4. 0.237788
   
5. awk 'BEGIN{print rand()}'
   
6. 0.237788

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单独执行这个rand的时候，为何每次都是生成同一个值呢？

1. awk 'BEGIN{base1=rand();base2=rand();base3=rand();print base1,base2,base3}'
   
2. 0.237788 0.291066 0.845814

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awk生成的这随机数真tmd假。。。
难道必须要先用srand来救场么？

prcardin

bulletmarquis

回复 2# prcardin


    难道和awk的版本都有关系？

   我的awk是3.1.6

LikeLx

回复 3# bulletmarquis
我的3.1.5的和你的结果一样

   

Shell_HAT

1. awk 'BEGIN{srand();print rand()}'

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reyleon

回复 1# bulletmarquis


    是时候祭出手册页说明了!!

1. In most awk implementations, including gawk, rand() starts generating numbers from the same starting number, or seed, each time you run awk. Thus, a program generates the same results each time you run it. The numbers are random within one awk run but predictable from run to run. This is convenient for debugging, but if you want a program to do different things each time it is used, you must change the seed to a value that is different in each run. To do this, use srand().
   

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bulletmarquis

回复 5# Shell_HAT


    srand我清楚，奇怪的是为啥用rand生成的时候，随机数永远是不变的呢？

   中间用一次srand，但下回单独rand的时候，值还是不变

1. awk 'BEGIN{print rand()}'
   
2. 0.237788
   
3. awk 'BEGIN{srand();print rand()}'
   
4. 0.903073
   
5. awk 'BEGIN{print rand()}'
   
6. 0.237788

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jcdiy0601

回复 1# bulletmarquis


    尽然真是这样。。。

Shell_HAT

回复 7# bulletmarquis


    请看6楼

bulletmarquis

回复 9# Shell_HAT


    看着英文就头疼，只好祭出百度翻译了。。。