syntax

What does this caret ^ syntax, with void on either side mean? [duplicate]

由 廉价感情. 提交于 2020-01-08 17:17:46
问题 This question already has answers here : Caret character between types rather than variables, surrounded by parentheses (2 answers) Closed 5 years ago . In iPhone SDK 4.0, UIApplication has a new method, setKeepAliveTimeout: that requires a second parameter of type void(^)(void) . -(BOOL)setKeepAliveTimeout:(NSTimeInterval)timeout handler:(void(^)(void))keepAliveHandler What exactly does the syntax of the second parameter mean, and how would I declare a function/handler that I can pass into

How do I modify a MySQL column to allow NULL?

由 别说谁变了你拦得住时间么 提交于 2020-01-08 12:02:26
问题 MySQL 5.0.45 What is the syntax to alter a table to allow a column to be null, alternately what's wrong with this: ALTER mytable MODIFY mycolumn varchar(255) null; I interpreted the manual as just run the above and it would recreate the column, this time allowing null. The server is telling me I have syntactical errors. I just don't see them. 回答1: You want the following: ALTER TABLE mytable MODIFY mycolumn VARCHAR(255); Columns are nullable by default. As long as the column is not declared

How do I modify a MySQL column to allow NULL?

由 百般思念 提交于 2020-01-08 12:02:08
问题 MySQL 5.0.45 What is the syntax to alter a table to allow a column to be null, alternately what's wrong with this: ALTER mytable MODIFY mycolumn varchar(255) null; I interpreted the manual as just run the above and it would recreate the column, this time allowing null. The server is telling me I have syntactical errors. I just don't see them. 回答1: You want the following: ALTER TABLE mytable MODIFY mycolumn VARCHAR(255); Columns are nullable by default. As long as the column is not declared

How to understand this Arrays and loops in Ruby? [closed]

由 谁说胖子不能爱 提交于 2020-01-07 08:47:11
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 8 years ago . Regarding the following code: update: (thank you DGM and The Tin Man for recomendation on code and apneadiving for explanation.) ################# # get main page ################# rows = doc.xpath('//table[

Parse Error in C [closed]

由 好久不见. 提交于 2020-01-07 08:04:50
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I'm doing some bitwise operation homework and it says my code has a "parse error" I'm assuming its the syntax or something...but I can't find a missing semi-colon or anything. Could you please spot why I might be

Parse Error in C [closed]

由 |▌冷眼眸甩不掉的悲伤 提交于 2020-01-07 08:04:21
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I'm doing some bitwise operation homework and it says my code has a "parse error" I'm assuming its the syntax or something...but I can't find a missing semi-colon or anything. Could you please spot why I might be

String cutting off during insert query [duplicate]

由 一曲冷凌霜 提交于 2020-01-07 07:59:09
问题 This question already has an answer here : Syntax error due to using a reserved word as a table or column name in MySQL (1 answer) Closed 5 years ago . Why is this doing what it's doing? Code: <?php if (isset($_POST['sourceInsert'])) { $url = $db_con3->real_escape_string($_POST['url']); $desc = $db_con3->real_escape_string($_POST['desc']); echo '$urlbefore is ' . $url . '<br />'; ///for troubleshooting $result = $db_con3->query("INSERT INTO gdrive_links (evalid, userid, url, desc) VALUES ('

for the right syntax to use near &apos;&apos;X&apos;&apos;问题解决

由 故事扮演 提交于 2020-01-07 06:15:25
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> BUG: Error Number: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''4'' at line 1 SELECT a.*,b.user_nickname, b.user_head_url from qk_user_album a, qk_user b where a.album_user_id = b.user_id ORDER BY a.album_create_date desc LIMIT 0, '4'; Filename: D:\DEV_PHP\WAMP\www\qk\system\database\DB_driver.php Line Number: 330 问题解决： 这里用到的是limit语法，两个参数应该都是数字，不应该出现字符串 查明的原因是PHP传递参数的时候，第二参数没有做转换，加一个intval函数，字符串转数字即可 来源： oschina 链接： https://my.oschina.net/u/855386/blog/370883

Implementing RelayCommand (MVVM) in VB.NET: Syntax problems

由 妖精的绣舞 提交于 2020-01-07 04:44:25
问题 For a project I have to use VB.NET. I am going to use MVVM, so I have to implement a RelayCommand class. In C#, the class looks like this: class ActionCommand : ICommand { private Action<object> execute; private Predicate<object> canExecute; private event EventHandler CanExecuteChangedInternal; public ActionCommand(Action<object> execute) : this(execute, DefaultCanExecute) { } public ActionCommand(Action<object> exec, Predicate<object> canExec) { if (exec == null) throw new

Can someone walk me through this line

由 ぃ、小莉子 提交于 2020-01-07 03:15:07
问题 var types = { "Grocery": "gro", "Restaurant": "res", "Bar": "bar", "Pizza Delivery": "piz", "Quick Service": "qui", "Retail": "ret", "Salon": "sal" } $(".type_changer").attr("id", types[$(this).text()]); I understand that the class type_changer id is being changed to the part of this array but I don't understand types[$(this).text()] and this line $(this).parents('.select-holder').find('.text').text($(this).text()); seems almost understandable but I get confused on the .parents and the .find(
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