string-concatenation

问题 Provided an HTML element of type div , how to set the value of its id attribute, which is the concatenation of a scope variable and a string ? 回答1: ngAttr directive can totally be of help here, as introduced in the official documentation https://docs.angularjs.org/guide/interpolation#-ngattr-for-binding-to-arbitrary-attributes For instance, to set the id attribute value of a div element, so that it contains an index, a view fragment might contain <div ng-attr-id="{{ 'object-' + myScopeObject

问题 I was wondering how one might go about writing a string concatenation operator in R, something like || in SAS, + in Java/C# or & in Visual Basic. The easiest way would be to create a special operator using %, like `%+%` <- function(a, b) paste(a, b, sep=\"\") but this leads to lots of ugly % \'s in the code. I noticed that + is defined in the Ops group, and you can write S4 methods for that group, so perhaps something like that would be the way to go. However, I have no experience with S4

问题 How do I get the promoPrice variable to print as part of the string ONLY $4.67 ? <c:set var=\"promoPrice\" value=\"4.67\" /> <p>${(promoPrice != null) ? \"ONLY $${promoPrice}\" : \"FREE\"}</p> 回答1: If you're already on EL 3.0 (Java EE 7; WildFly, Tomcat 8, GlassFish 4, etc), then you could use the new += operator for this: <p>${not empty promoPrice ? 'ONLY $' += promoPrice : 'FREE'}</p> If you're however not on EL 3.0 yet, then use EL 2.2 (Java EE 7; JBoss AS 6/7, Tomcat 7, GlassFish 3, etc)

问题 This question already has an answer here: How to use GROUP BY to concatenate strings in SQL Server? 17 answers If I have a table like this: +------------+ | Id | Value | +------------+ | 1 | \'A\' | |------------| | 1 | \'B\' | |------------| | 2 | \'C\' | +------------+ How can I get a resultset like this: +------------+ | Id | Value | +------------+ | 1 | \'AB\' | |------------| | 2 | \'C\' | +------------+ I know this is really easy to do in MySQL using GROUP_CONCAT, but I need to be able

问题 I have this code: a = \"xyz\" g = \"abcd \" & a After running it, the value of g is abcd xyz . However, I want quotes around the value of a in g . After running the code, g should be abcd \"xyz\" instead. How can I accomplish this? 回答1: You can escape by doubling the quotes g="abcd """ & a & """" or write an explicit chr() call g="abcd " & chr(34) & a & chr(34) 回答2: You have to use double double quotes to escape the double quotes (lol): g = "abcd """ & a & """" 回答3: I usually do this: Const Q

问题 I need to know if its possible to concatenate strings, as follows ? and if not, what is the alternative of doing so ? while ($personCount < 10) { $result+= $personCount . \"person \"; } echo $result; it should appear like 1 person 2 person 3 person etc.. You cann\'t use the + sign in concatenation so what is the alternative ? 回答1: Just use . for concatenating. And you missed out the $personCount increment! while ($personCount < 10) { $result .= $personCount . ' people'; $personCount++; } echo

问题 What is the most efficient way to write the old-school: StringBuilder sb = new StringBuilder(); if (strings.Count > 0) { foreach (string s in strings) { sb.Append(s + \", \"); } sb.Remove(sb.Length - 2, 2); } return sb.ToString(); ...in LINQ? 回答1: This answer shows usage of LINQ ( Aggregate ) as requested in the question and is not intended for everyday use. Because this does not use a StringBuilder it will have horrible performance for very long sequences. For regular code use String.Join as

问题 All, I have a large (unavoidable) dynamic SQL query. Due to the number of fields in the selection criteria the string containing the dynamic SQL is growing over 4000 chars. Now, I understand that there is a 4000 max set for NVARCHAR(MAX) , but looking at the executed SQL in Server Profiler for the statement DELARE @SQL NVARCHAR(MAX); SET @SQL = \'SomeMassiveString > 4000 chars...\'; EXEC(@SQL); GO Seems to work(!?), for another query that is also large it throws an error which is associated

问题 This question already has an answer here: SQL Query to concatenate column values from multiple rows in Oracle 11 answers I have a table that looks like this: A 1 A 2 B 1 B 2 And I want to produce a result set that looks like this: A 1 2 B 1 2 Is there a SQL statement that will do this? I am using Oracle. Related questions: Returning multiple rows from a single row My question is close to the opposite of this question. Use LINQ to concatenate This is exactly what I want to do, but without LINQ

问题 What is the string concatenation operator in Oracle SQL? Are there any \"interesting\" features I should be careful of? (This seems obvious, but I couldn\'t find a previous question asking it). 回答1: It is || , for example: select 'Mr ' || ename from emp; The only "interesting" feature I can think of is that 'x' || null returns 'x' , not null as you might perhaps expect. 回答2: There's also concat, but it doesn't get used much select concat('a','b') from dual; 回答3: I would suggest concat when