Recent questions tagged null

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null - About the non-nullable types debate

I keep hearing people talk about how non-nullable reference types would solve so many bugs and make programming so ... figure it out yourself? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - Does Ruby have syntax for safe navigation operator of nil values, like in Groovy?

In Groovy, there is a nice syntax for working with null values. For example, I can do an if statement: if ( ... is a Ruby equivalent I missed. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - Linq error generic parameter or the query must use a nullable type

I got this error when i use sum function in LINQ: The cast to value type 'Decimal' failed because the ... Amount==null?0:Content.Amount), See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - F#: Why aren't option types compatible with nullable types?

Why aren't option types like "int option" compatible with nullable types like "Nullable"? I assume there ... like the Nullable structure. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - F#: Why aren't option types compatible with nullable types?

Why aren't option types like "int option" compatible with nullable types like "Nullable"? I assume there ... like the Nullable structure. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - Why should someone use {} for initializing an empty object in R?

It seems that some programmers are using: a = {} a$foo = 1 a$bar = 2 What is the benefit over a = list(foo ... would do the same, wouldn't it? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - How can I memoize a method that may return true, false, or nil in Ruby?

Obviously ||= won't work def x? @x_query ||= expensive_way_to_calculate_x end because if it turns out ... otherwise completely correct answer. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - Why shouldn't I always use nullable types in C#

I've been searching for some good guidance on this since the concept was introduced in .net 2.0. Why would I ... types? Thanks for your time, See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - Why did father of Clojure say that Scheme's true/false are broken?

In this video, Rich Hickey introduced Clojure for Lisp programmers. At time 01:10:42, he talked about nil/false/ ... he consider it's "broken"? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - where is __null defined in g++?

in g++, NULL is defined as __null, in 64-bit case, __null is 8 bytes. such as: printf("sizeof(__null): ... ):4 however, where is __null defined? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - Is It Necessary to Set Pointers to nil in Objective-C After release?

Is there anything wrong with doing something like NSString * string = [ [ NSString alloc ] init ]; ... [ string ... also adding string = nil; ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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406 views

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null - Standard SQL boolean operator IS vs. equals (=) operator

On the Wikipedia page for SQL there are some truth tables about boolean logic in SQL. [1] The Wikipedia page ... SQL:2003 draft PDF page 397 See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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null - ASP.NET MVC, strongly typed views, partial view parameters glitch

If i got view which inherits from: System.Web.Mvc.ViewPage<Foo> Where Foo has a property Bar with a type string ... , where it should pass null? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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400 views

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null - In Ruby, why does nil[1]=1 evaluate to nil?

For example: nil[1] #=> NoMethodError nil[1]=1 #=> nil It's not just syntax, as it happens with variables too: a ... > #<Method...> Ruby 2.3.0p0 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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399 views

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null - How to add a conditional unique index on PostgreSQL

I have a line_items table with following columns: product_id variant_id variant_id is nullable. Here is the ... possible in PostgreSQL? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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573 views

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null - Removing "NUL" characters

I have got characters like that in my notepad++ When i am trying to copy whole line, i am actually copying ... problem, just the effect(NULs) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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