C++, PHP, Javascript,..., support for lambda expressions

lambda

lambda expression, also called Closure (closure), also called anonymous function. Due to its power, it is supported by almost all mainstream development languages. This article attempts to list sample codes for lambda expressions in most languages ​​and will be continuously updated in the future.

PHP’s support for lambdas

<code><span><?php</span><span>$i</span> = <span>12</span>;
<span>$j</span> = <span>33</span>;
<span>$callable</span> = <span><span>function</span><span>()</span><span>use</span><span>(<span>$i</span>, &<span>$j</span>)</span>
{</span><span>echo</span><span>$i</span> . <span>"\n"</span>;
    <span>echo</span><span>$j</span> . <span>"\n"</span>;
};

<span>$callable</span>();

<span>$i</span>++;
<span>$j</span>++;

<span>$callable</span>();
</code>

• must explicitly reference external variables, distinguishing between value and reference passing.

C++’s support for lambda

<code><span>#include <iostream></span><span>using</span><span>namespace</span><span>std</span>;

<span>int</span> main(<span>int</span> argc, <span>char</span>** argv)
{
    <span>int</span> i = <span>12</span>;
    <span>int</span> j = <span>33</span>;
    <span>auto</span> callable = [i, &j](){
        <span>cout</span> << i << endl;
        <span>cout</span> << j << endl;
    };

    callable();

    i++;
    j++;

    callable();
}
</code>

• must explicitly refer to external variables, distinguishing between value transfer and reference transfer.
• Supports simple syntax such as [=][&] to reference all external variables.

Javascript

<code><script>
var <span>i</span> = <span>12</span>;
var <span>j</span> = <span>33</span>;

var callable = <span><span>function</span><span>()</span>{</span>
    alert(<span>i</span>);
    alert(<span>j</span>);
}

callable();

<span>i</span>++;
<span>j</span>++;

callable();
</script</code>

• No need to reference external variables, external variables are automatically available.
• All variables are passed by reference.

The above has introduced the support for lambda expressions in C++, PHP, Javascript, ..., including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.