速战速决 (3) - PHP: 函数基础, 函数参数, 函数返回值, 可变函数, 匿名函数, 闭包函数, 回调函数
作者：webabcd
介绍
速战速决 之 PHP
- 函数基础
- 函数参数
- 函数返回值
- 可变函数
- 匿名函数
- 闭包函数
- 回调函数
示例
1、函数的相关知识点 1（基础）
function/function1.php
<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
* 函数的相关知识点 1（基础）
</span><span style="color: #008000;">*/</span>
<span style="color: #008000;">//</span><span style="color: #008000;"> 可以在相关的 function 声明语句之前调用该函数</span>
<span style="color: #000000;">f1();
</span><span style="color: #0000ff;">function</span><span style="color: #000000;"> f1()
{
</span><span style="color: #0000ff;">echo</span> "f1"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 这里调用 f2() 就错误了
// f2();</span>
<span style="color: #800080;">$b</span> = <span style="color: #0000ff;">true</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$b</span><span style="color: #000000;">)
{
</span><span style="color: #0000ff;">function</span> f2() <span style="color: #008000;">//</span><span style="color: #008000;"> 条件成立才会声明此函数</span>
<span style="color: #000000;"> {
</span><span style="color: #0000ff;">echo</span> "f2"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
}
f2();
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 这里调用 f4() 就错误了（因为 f4 的声明是在 f3 的内部，所以要先调用 f3 才能再调用 f4）
// f4();</span>
<span style="color: #000000;">f3();
f4();
</span><span style="color: #0000ff;">function</span><span style="color: #000000;"> f3()
{
</span><span style="color: #0000ff;">echo</span> "f3"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #0000ff;">function</span><span style="color: #000000;"> f4()
{
</span><span style="color: #0000ff;">echo</span> "f4"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
}</span>
2、函数的相关知识点 2（函数参数）
function/function2.php
<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
* 函数的相关知识点 2（函数参数）
</span><span style="color: #008000;">*/</span>
<span style="color: #008000;">//</span><span style="color: #008000;"> 带参数的函数</span>
f1("webabcd"<span style="color: #000000;">);
</span><span style="color: #0000ff;">function</span> f1(<span style="color: #800080;">$name</span><span style="color: #000000;">)
{
</span><span style="color: #0000ff;">echo</span> "hello " . <span style="color: #800080;">$name</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello webabcd</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 带参数的函数（参数是引用类型）</span>
<span style="color: #800080;">$name</span> = "webabcd"<span style="color: #000000;">;
f2(</span><span style="color: #800080;">$name</span><span style="color: #000000;">);
</span><span style="color: #0000ff;">function</span> f2(&<span style="color: #800080;">$n</span>) <span style="color: #008000;">//</span><span style="color: #008000;"> 参数是引用类型</span>
<span style="color: #000000;">{
</span><span style="color: #0000ff;">echo</span> "hello " . <span style="color: #800080;">$n</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello webabcd</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #800080;">$n</span> = "wanglei"; <span style="color: #008000;">//</span><span style="color: #008000;"> $n 是引用类型，其与全局变量 $name 指向的内容是一样的</span>
<span style="color: #000000;">}
</span><span style="color: #0000ff;">echo</span> "hello " . <span style="color: #800080;">$name</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello wanglei</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 带参数的函数（参数可以指定默认值）</span>
f3("hello "); <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello webabcd</span>
f3("hello ", "wanglei"); <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello wanglei</span>
<span style="color: #0000ff;">function</span> f3(<span style="color: #800080;">$p1</span>, <span style="color: #800080;">$p2</span> = "webabcd") <span style="color: #008000;">//</span><span style="color: #008000;"> 参数的默认值只能是常量，不能是表达式</span>
<span style="color: #000000;">{
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$p1</span> . <span style="color: #800080;">$p2</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}</span>
3、函数的相关知识点 3（函数返回值）
function/function3.php
<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
* 函数的相关知识点 3（函数返回值）
</span><span style="color: #008000;">*/</span>
<span style="color: #008000;">//</span><span style="color: #008000;"> 带返回值的函数</span>
<span style="color: #800080;">$result1</span> = f1("webabcd"<span style="color: #000000;">);
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$result1</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #0000ff;">function</span> f1(<span style="color: #800080;">$name</span><span style="color: #000000;">)
{
</span><span style="color: #0000ff;">return</span> "hello " . <span style="color: #800080;">$name</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello webabcd</span>
<span style="color: #000000;">}
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 从函数返回以一个引用（函数的声明和调用都要加 &）</span>
<span style="color: #800080;">$result2</span> = &<span style="color: #000000;">f2();
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$result2</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: 1</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #800080;">$result2</span> = 100; <span style="color: #008000;">//</span><span style="color: #008000;"> $result2 是个引用，指向 $i 所指向的内容，所以此句之后 $i 的值为 100</span>
<span style="color: #800080;">$result3</span> = &<span style="color: #000000;">f2();
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$result3</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: 101</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #0000ff;">function</span> &f2() <span style="color: #008000;">//</span><span style="color: #008000;"> 此函数会返回一个引用（函数的声明和调用都要加 &）</span>
<span style="color: #000000;">{
</span><span style="color: #0000ff;">static</span> <span style="color: #800080;">$i</span> = 0<span style="color: #000000;">;
</span><span style="color: #800080;">$i</span> ++<span style="color: #000000;">;
</span><span style="color: #0000ff;">return</span> <span style="color: #800080;">$i</span><span style="color: #000000;">;
}</span>
4、函数的相关知识点 4（可变函数，匿名函数，闭包函数）
function/function4.php
<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
* 函数的相关知识点 4（可变函数，匿名函数，闭包函数）
</span><span style="color: #008000;">*/</span>
<span style="color: #008000;">//</span><span style="color: #008000;"> variable function（可变函数），将变量的值作为函数名</span>
<span style="color: #0000ff;">function</span><span style="color: #000000;"> f1()
{
</span><span style="color: #0000ff;">echo</span> "f1"; <span style="color: #008000;">//</span><span style="color: #008000;"> output: f1</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #0000ff;">function</span><span style="color: #000000;"> f2()
{
</span><span style="color: #0000ff;">echo</span> "f2"; <span style="color: #008000;">//</span><span style="color: #008000;"> output: f2</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #800080;">$func</span> = 'f1'<span style="color: #000000;">;
</span><span style="color: #800080;">$func</span><span style="color: #000000;">();
</span><span style="color: #800080;">$func</span> = 'f2'<span style="color: #000000;">;
</span><span style="color: #800080;">$func</span><span style="color: #000000;">();
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 匿名函数</span>
<span style="color: #0000ff;">echo</span> <span style="color: #008080;">preg_replace_callback</span> <span style="color: #008000;">//</span><span style="color: #008000;"> output: userName</span>
<span style="color: #000000;">(
</span>'~-([a-z])~',
<span style="color: #0000ff;">function</span> (<span style="color: #800080;">$match</span>) <span style="color: #008000;">//</span><span style="color: #008000;"> 匿名函数</span>
<span style="color: #000000;"> {
</span><span style="color: #0000ff;">return</span> <span style="color: #008080;">strtoupper</span>(<span style="color: #800080;">$match</span>[1<span style="color: #000000;">]);
}</span>,
'user-name'<span style="color: #000000;">
);
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 闭包函数
// $f3("webabcd"); // 这是错误的，对于闭包函数来说，调用时要在声明语句的后面</span>
<span style="color: #800080;">$f3</span> = <span style="color: #0000ff;">function</span>(<span style="color: #800080;">$name</span><span style="color: #000000;">)
{
</span><span style="color: #0000ff;">echo</span> "hello " . <span style="color: #800080;">$name</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: hello webabcd</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}; </span><span style="color: #008000;">//</span><span style="color: #008000;"> 别忘了闭包函数的“;”</span>
<span style="color: #800080;">$f3</span>("webabcd");
5、函数的相关知识点 5（回调函数）
function/function5.php
<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
* 函数的相关知识点 5（回调函数）
</span><span style="color: #008000;">*/</span>
<span style="color: #008000;">//</span><span style="color: #008000;"> 用于演示如何回调（callback）函数</span>
<span style="color: #0000ff;">function</span><span style="color: #000000;"> myCallbackFunction()
{
</span><span style="color: #0000ff;">return</span> 'myCallbackFunction'<span style="color: #000000;">;
}
</span><span style="color: #0000ff;">class</span><span style="color: #000000;"> MyClass1
{
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 用于演示如何回调（callback）实例方法</span>
<span style="color: #0000ff;">public</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> myMethod1()
{
</span><span style="color: #0000ff;">echo</span> 'MyClass1 myMethod1'<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> '<br>'<span style="color: #000000;">;
}
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 用于演示如何回调（callback）类方法</span>
<span style="color: #0000ff;">public</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> myMethod2()
{
</span><span style="color: #0000ff;">echo</span> 'MyClass1 myMethod2'<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> '<br>'<span style="color: #000000;">;
}
}
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 call_user_func 调用指定的函数</span>
<span style="color: #0000ff;">echo</span> <span style="color: #008080;">call_user_func</span>('myCallbackFunction'<span style="color: #000000;">);
</span><span style="color: #0000ff;">echo</span> '<br>'<span style="color: #000000;">;
</span><span style="color: #800080;">$obj1</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> MyClass1();
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 call_user_func 调用指定对象的指定方法</span>
<span style="color: #008080;">call_user_func</span>(<span style="color: #0000ff;">array</span>(<span style="color: #800080;">$obj1</span>, 'myMethod1'<span style="color: #000000;">));
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 call_user_func 调用指类的类方法</span>
<span style="color: #008080;">call_user_func</span>(<span style="color: #0000ff;">array</span>('MyClass1', 'myMethod2'<span style="color: #000000;">));
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 call_user_func 调用指类的类方法（PHP 5.2.3 或以上）</span>
<span style="color: #008080;">call_user_func</span>('MyClass1::myMethod2');
OK
[源码下载]
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