Perl的grep和地图有什么作用？

Question

这段代码实际上做了什么？

@array = ( 'hai','hello','bar','foo' ) ;

print grep (/hai/ , @array );
print grep ("hai",@array ) ;
print map (/hai/ , @array );
print map ("hai",@array ) ;

Answer 1

它调用map和grep函数。可以在perlfunc和grep的map条目中找到相关说明。

今天Google被打破了吗？

Answer 2

尝试一下......

print grep (/hai/ , @array );
hai
# writes all elements from @array containing 'hai' in them

print grep ("hai",@array ) ;
haihellobarfoo
# writes all elements, because "hai" evaluates to true

print map (/hai/ , @array );
1
# writes 1 for the only element from the @array, that contains 'hai'

print map ("hai",@array ) ;
haihaihaihai
# maps 'hai' to each element from @array