c++ - What is this smiley-with-beard expression: "<:]{%>"?

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Top 5 Answer for c++ - What is this smiley-with-beard expression: "<:]{%>"?

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The program uses digraphs to represent the following:

[] {}; 

This is a lambda expression that does nothing. The corresponding symbols have these equivalents:

<: = [ %> = } 

Though they are generally unneeded today, digraphs are useful for when your keyboard lacks certain keys necessary to use C++'s basic source character set, namely the graphical ones. The combination of the characters that make up a digraph are processed as a single token. This in turn makes up for any insufficiently-equipped keyboards or other such hardware or software.

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That's an empty lambda using a digraph disguise. Normal lambdas don't have beards.

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The program is using digraphs, which allow C++ programming with keyboards (or text encodings) that may not have the characters C++ typically uses.

The code resolves to this:

int main(){   []{}; // smile! } 
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int main(){   <:]{%>; // smile! } 

It's basically a Lambda expression (Lambda expression is one of C++11 features) using digraphs (both digraphs and trigraphs works on C++):

[] {}; 

Using only digraphs:

<:]<%};   <:]<%%>;  [:>{%>; // like my cubic hat?  [:><%};  [:><%%>; 

Mixing them with Trigraphs:

<:??)<%??>; // popeye  ??(:>{??>; // pirate 
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Get Drawable from vector resource irrespective of, whether its vector or not:

AppCompatResources.getDrawable(context, R.drawable.icon); 

ContextCompat.getDrawable(context, R.drawable.icon); will produce android.content.res.Resources$NotFoundException for vector resource.

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