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What is the difference between null and undefined in JavaScript?
... that indicates an absence of value.
think about it as a value, like:
"foo" is string,
true is boolean ,
1234 is number,
null is undefined.
undefined property indicates that a variable has not been assigned a value including null too .
Like
var foo;
defined empty variable is n...
Redirect stderr and stdout in Bash
... If you want to append to a file then you must do it this way: echo "foo" 2>&1 1>> bar.txt AFAIK there's no way to append using &>
– SlappyTheFish
Jun 8 '10 at 10:58
...
In Objective-C why should I check if self = [super init] is not nil?
...nil after initializing a variable and before calling functions on it? e.g. Foo *bar = [[Foo alloc] init]; if (bar) {[bar doStuff];}
– dev_does_software
Sep 4 '13 at 19:14
...
HttpSecurity, WebSecurity and AuthenticationManagerBuilder
...gure(HttpSecurity http) method implementations invoking http.antMatchers("/foo").permitAll()" which seems equivalent to invoking web.ignoring().antMatchers("/foo") in the configure(WebSecurity web) method.
– chrisinmtown
Jul 26 '19 at 12:53
...
“unpacking” a tuple to call a matching function pointer
...S> struct gens<0, S...>{ typedef seq<S...> type; };
double foo(int x, float y, double z)
{
return x + y + z;
}
template <typename ...Args>
struct save_it_for_later
{
std::tuple<Args...> params;
double (*func)(Args...);
double delayed_dispatch()
{
return ca...
Create dynamic URLs in Flask with url_for()
...
It takes keyword arguments for the variables:
url_for('add', variable=foo)
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How do I wrap link_to around some html ruby code?
...
For older Rails versions, you can use
<% content_tag(:a, :href => foo_path) do %>
<span>Foo</span>
<% end %>
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Escape double quotes in a string
...g character " to the string.
What problem is that? You can't type string foo = "Foo"bar"";, because that'll invoke a compile error. As for the adding part, in string size terms that is not true:
@"""".Length == "\"".Length == 1
...
Default string initialization: NULL or Empty? [closed]
... a lot:
string name = null; // or String.Empty
if (condition)
{
name = "foo";
}
else
{
name = "bar";
}
return name;
Not initializing to null would be just as effective. Furthermore, most often you want a value to be assigned. By initializing to null, you can potentially miss code paths that ...
Vim: Creating parent directories on save
If I invoke vim foo/bar/somefile but foo/bar don't already exist, Vim refuses to save.
6 Answers
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