parentheses

问题 I am accustomed to testing that a variable has a non-null value (or give a message and bail) using a line like this: test $variable || (echo "Value of \$variable cannot be null."; exit 1) I'm quite new to using functions in my scripts, but I've got a case where I need to be sure a non-null value is passed or bail out of the function. However the command grouping for the "or" case is not working the same way inside the function. I wrote this little test script to demonstrate: $ cat -n bubu.sh

问题 I was reading about list monads and encountered: [1,2] >>= \n -> ['a','b'] >>= \ch -> return (n,ch) it produces [(1,'a'),(1,'b'),(2,'a'),(2,'b')] Here's how I understand it: Implicit parentheses are: ([1,2] >>= \n -> ['a','b']) >>= (\ch -> return (n,ch)) ([1,2] >>= \n -> ['a','b']) should give [('a',1),('b',1),('a',2),('b',2)] because instance Monad [] where return x = [x] xs >>= f = concat (map f xs) -- this line fail _ = [] so concat (map f xs) is concat (map (\n -> ['a','b']) [1,2]) which

问题 I was reading about list monads and encountered: [1,2] >>= \n -> ['a','b'] >>= \ch -> return (n,ch) it produces [(1,'a'),(1,'b'),(2,'a'),(2,'b')] Here's how I understand it: Implicit parentheses are: ([1,2] >>= \n -> ['a','b']) >>= (\ch -> return (n,ch)) ([1,2] >>= \n -> ['a','b']) should give [('a',1),('b',1),('a',2),('b',2)] because instance Monad [] where return x = [x] xs >>= f = concat (map f xs) -- this line fail _ = [] so concat (map f xs) is concat (map (\n -> ['a','b']) [1,2]) which

问题 I have data imported from a .csv file. The first column contains character strings that contain text within parentheses. The data look like: symbol ___________________________________________ 1 | Apollo Senior Floating Rate Fund Inc. (AFT) 2 | Apollo Tactical Income Fund Inc. (AIF) 3 | Altra Industrial Motion Corp. (AIMC) 4 | Allegion plc (ALLE) 5 | Amphenol Corporation (APH) 6 | Ares Management Corporation (ARES) 7 | ARMOUR Residential REIT, Inc. (ARR) 8 | Banc of California, Inc. (BANC) 9 |

问题 Is there a difference in writing: throw SomeException; and throw(SomeException); I have seen some sources that claim the latter (with parentheses) is not a good option for some reason but alas I can not recall where I've seen this. 回答1: There should not be any functionality difference between the two expressions apart from the parentheses. I have never heard of any clear reason that says why one should be superior to the other. To me the first option looks more intuitive as it does not

问题 Is there a difference in writing: throw SomeException; and throw(SomeException); I have seen some sources that claim the latter (with parentheses) is not a good option for some reason but alas I can not recall where I've seen this. 回答1: There should not be any functionality difference between the two expressions apart from the parentheses. I have never heard of any clear reason that says why one should be superior to the other. To me the first option looks more intuitive as it does not

问题 Is there a difference in writing: throw SomeException; and throw(SomeException); I have seen some sources that claim the latter (with parentheses) is not a good option for some reason but alas I can not recall where I've seen this. 回答1: There should not be any functionality difference between the two expressions apart from the parentheses. I have never heard of any clear reason that says why one should be superior to the other. To me the first option looks more intuitive as it does not

问题 Is there a difference in writing: throw SomeException; and throw(SomeException); I have seen some sources that claim the latter (with parentheses) is not a good option for some reason but alas I can not recall where I've seen this. 回答1: There should not be any functionality difference between the two expressions apart from the parentheses. I have never heard of any clear reason that says why one should be superior to the other. To me the first option looks more intuitive as it does not

问题 Is there a difference in writing: throw SomeException; and throw(SomeException); I have seen some sources that claim the latter (with parentheses) is not a good option for some reason but alas I can not recall where I've seen this. 回答1: There should not be any functionality difference between the two expressions apart from the parentheses. I have never heard of any clear reason that says why one should be superior to the other. To me the first option looks more intuitive as it does not

问题 I'm just wondering how I could remove the text between a set of parentheses and the parentheses themselves in php. Example : ABC (Test1) I would like it to delete (Test1) and only leave ABC Thanks 回答1: $string = "ABC (Test1)"; echo preg_replace("/\([^)]+\)/","",$string); // 'ABC ' preg_replace is a perl-based regular expression replace routine. What this script does is matches all occurrences of a opening parenthesis, followed by any number of characters not a closing parenthesis, and again