C# – How to Differentiate Between Curly Braces {} and Brackets [] When Initializing Arrays in C#

.netc++

I am really curious to know what is the different between these lines?

//with curly braces
int[] array2 = { 1, 2, 3, 4, };
//with brackets
int[] array3 = [1, 2, 3, 4,];

Console.WriteLine(array2[1]);
Console.WriteLine(array3[1]);

//the output is the same.

I want to know what is the different between using curly braces and brackets while initializing values.

Best Answer

In the example you've given, they mean the same thing. But collection expressions are in general more flexible. In particular:

They can create instances of collections other than arrays
They can use the spread operator to include sequences

For example:

ImmutableList<int> x = [0, .. Enumerable.Range(100, 5), 200];

That creates an immutable list of integers with values 0, 100, 101, 102, 103, 104, 200.

Note that while collection initializers can also be used to initialize non-array collection types in a somewhat flexible way, they're more limited than collection expressions and still require the new part. So for example:

// Valid
List<int> x = new() { 1, 2, 3 };

// Not valid
List<int> x = { 1, 2, 3 };

// Not valid (collection initializers assume mutability)
ImmutableList<int> x = new() { 1, 2, 3 };

Collection expressions address both of these concerns.

Related Solutions

C# String – Case Insensitive Contains Method

You could use the String.IndexOf Method and pass StringComparison.OrdinalIgnoreCase as the type of search to use:

string title = "STRING";
bool contains = title.IndexOf("string", StringComparison.OrdinalIgnoreCase) >= 0;

Even better is defining a new extension method for string:

public static class StringExtensions
{
    public static bool Contains(this string source, string toCheck, StringComparison comp)
    {
        return source?.IndexOf(toCheck, comp) >= 0;
    }
}

Note, that null propagation ?. is available since C# 6.0 (VS 2015), for older versions use

if (source == null) return false;
return source.IndexOf(toCheck, comp) >= 0;

USAGE:

string title = "STRING";
bool contains = title.Contains("string", StringComparison.OrdinalIgnoreCase);

C# – How to Escape Braces in a Format String

For you to output foo {1, 2, 3} you have to do something like:

string t = "1, 2, 3";
string v = String.Format(" foo {{{0}}}", t);

To output a { you use {{ and to output a } you use }}.

Or now, you can also use C# string interpolation like this (a feature available in C# 6.0)

Escaping brackets: String interpolation $(""). It is new feature in C# 6.0.

var inVal = "1, 2, 3";
var outVal = $" foo {{{inVal}}}";
// The output will be:  foo {1, 2, 3}

Best Answer

Related Solutions

C# String – Case Insensitive Contains Method

C# – How to Escape Braces in a Format String

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