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Error “initializer element is not constant” when trying to initialize variable with const
...n object that has static storage duration shall be constant expressions or string literals.
In section 6.6, the spec defines what must considered a constant expression. No where does it state that a const variable must be considered a constant expression. It is legal for a compiler to extend thi...
Make a float only show two decimal places
...ored, it is a matter of how you are displaying it. When converting it to a string you must round to the desired precision, which in your case is two decimal places.
E.g.:
NSString* formattedNumber = [NSString stringWithFormat:@"%.02f", myFloat];
%.02f tells the formatter that you will be formatt...
React.js: onChange event for contentEditable
...opTypes.func,
onChange: PropTypes.func.isRequired,
text: PropTypes.string,
placeholder: PropTypes.string,
editable: PropTypes.bool
},
getDefaultProps() {
return {
component: React.DOM.div,
editable: false
};
},
getInitialState() {
return {
init...
Using Enum values as String literals
What is the best way to use the values stored in an Enum as String literals?
For example:
18 Answers
...
What uses are there for “placement new”?
... on a
pre-allocated buffer takes less time):
char *buf = new char[sizeof(string)]; // pre-allocated buffer
string *p = new (buf) string("hi"); // placement new
string *q = new string("hi"); // ordinary heap allocation
You may also want to be sure there can be no allocation failure at ...
PHP validation/regex for URL
...
Use the filter_var() function to validate whether a string is URL or not:
var_dump(filter_var('example.com', FILTER_VALIDATE_URL));
It is bad practice to use regular expressions when not necessary.
EDIT: Be careful, this solution is not unicode-safe and not XSS-safe. If yo...
JPush 极光推送扩展 · App Inventor 2 中文网
...步：监听推送事件
when JPush1.OnNotificationOpened(title, content, extras) {
标签1.Text = content
}
when JPush1.OnMessageReceived(message, extras) {
// 处理自定义消息（透传消息，不显示通知栏）
标签2.Text = message
}
获取设备注册 ID
...
How to rename items in values() in Django?
...
It's a bit hacky, but you could use the extra method:
MyModel.objects.extra(
select={
'renamed_value': 'cryptic_value_name'
}
).values(
'renamed_value'
)
This basically does SELECT cryptic_value_name AS renamed_value in the SQL.
Another option, if you al...
What is the relative performance difference of if/else versus switch statement in Java?
... First create some interface:
public interface Action {
void execute(String input);
}
And get hold of all implementations in some Map. You can do this either statically or dynamically:
Map<String, Action> actions = new HashMap<String, Action>();
Finally replace the if/else or ...
Get the generated SQL statement from a SqlCommand object?
...o the "text" command doesn't account for parameters etc
public static String ParameterValueForSQL(this SqlParameter sp)
{
String retval = "";
switch (sp.SqlDbType)
{
case SqlDbType.Char:
case SqlDbType.NChar:
case SqlDbType.NText:...