速战速决 (2) - PHP: 数据类型 bool, int, float, string, object, array - webabcd

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速战速决 (2) - PHP: 数据类型 bool, int, float, string, object, array

作者：webabcd


介绍
速战速决 之 PHP

• 数据类型 bool, int, float, string, object, array

示例
1、数据类型: bool, int, float, string, object
basic/type1.php

<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
 * 数据类型: bool, int, float, string, object
 </span><span style="color: #008000;">*/</span>

<span style="color: #008000;">//</span><span style="color: #008000;"> 布尔类型（true, false 不分大小写）</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;">echo</span> "true"<span style="color: #000000;">;
    </span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #800080;">$b</span> = <span style="color: #0000ff;">false</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">if</span> (!<span style="color: #800080;">$b</span><span style="color: #000000;">)
{
    </span><span style="color: #0000ff;">echo</span> "false"<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;"> 整型</span>
<span style="color: #800080;">$i</span> = 100<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$i</span><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;"> 八进制（以 0 开头）</span>
<span style="color: #800080;">$i</span> = 0144; <span style="color: #008000;">//</span><span style="color: #008000;"> 等于十进制的 100</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$i</span><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;"> 十六进制（以 0x 开头）</span>
<span style="color: #800080;">$i</span> = 0x64; <span style="color: #008000;">//</span><span style="color: #008000;"> 等于十进制的 100</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$i</span><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;"> 浮点型</span>
<span style="color: #800080;">$f</span> = 3.14<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$f</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #0000ff;">if</span> (!<span style="color: #008080;">is_nan</span>(<span style="color: #800080;">$f</span>)) <span style="color: #008000;">//</span><span style="color: #008000;"> 通过 is_nan 函数来判断一个变量的值是否不是数字类型</span>
<span style="color: #000000;">{
    </span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$f</span><span style="color: #000000;">;
    </span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$f</span> == 1.11 + 2.03) <span style="color: #008000;">//</span><span style="color: #008000;"> false</span>
<span style="color: #000000;">{
    </span><span style="color: #0000ff;">echo</span> "注意不要用 == 来比较两个浮点型变量"<span style="color: #000000;">;
    </span><span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #0000ff;">if</span> (<span style="color: #008080;">bccomp</span>(<span style="color: #800080;">$f</span>, 1.11 + 2.03, 2) == 0) <span style="color: #008000;">//</span><span style="color: #008000;"> true</span>
<span style="color: #000000;">{
    </span><span style="color: #0000ff;">echo</span> "请用 bccomp 函数来比较两个浮点型变量"<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;"> 字符串类型</span>
<span style="color: #800080;">$s</span> = 'abc$i\$'<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$s</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: abc$i\$</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #800080;">$s</span> = "abc<span style="color: #800080;">$i</span>\$"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$s</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: abc100$</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #0000ff;">if</span> (<span style="color: #008080;">is_string</span>(<span style="color: #800080;">$s</span>)) <span style="color: #008000;">//</span><span style="color: #008000;"> 通过 is_string 函数来判断一个变量的值是否是字符串类型</span>
<span style="color: #000000;">{
    </span><span style="color: #0000ff;">echo</span> "<span style="color: #800080;">$s</span> 是字符串"<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;"> 字符串的格式化输出</span>
<span style="color: #800080;">$s</span> = <span style="color: #008080;">sprintf</span>("string: %s, int: %d", "xyz", 100<span style="color: #000000;">);
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$s</span><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;"> heredoc 结构（通过“
<span style="color: #800080;">$h</span> = XXX
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$s</span><span style="color: #000000;">;
\\
XXX;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$h</span><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;">
上面 echo $h; 输出的内容如下：
echo abc100$;
\
</span><span style="color: #008000;">*/</span>

<span style="color: #008000;">//</span><span style="color: #008000;"> nowdoc 结构（通过“
<span style="color: #800080;">$n</span> = echo</span> <span style="color: #800080;">$s</span><span style="color: #000000;">;
\\
YYY;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$n</span><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;">
上面 echo $n; 输出的内容如下：
echo $s;
\\
</span><span style="color: #008000;">*/</span>


<span style="color: #008000;">//</span><span style="color: #008000;"> object 类型</span>
<span style="color: #800080;">$obj</span> = (<span style="color: #0000ff;">object</span>)"sss"; <span style="color: #008000;">//</span><span style="color: #008000;"> 将一个变量转换为对象时，系统会创建一个内置类，该类的 scalar 属性即为原变量的值</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$obj</span>->scalar; <span style="color: #008000;">//</span><span style="color: #008000;"> output: sss</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;


</span><span style="color: #008000;">//</span><span style="color: #008000;"> NULL 类型（NULL 不分大小写）</span>
<span style="color: #800080;">$n1</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> 未赋值则为 null</span>
<span style="color: #800080;">$n2</span> = <span style="color: #0000ff;">NULL</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$n1</span> == <span style="color: #0000ff;">null</span><span style="color: #000000;">)
{
    </span><span style="color: #0000ff;">echo</span> "null"; <span style="color: #008000;">//</span><span style="color: #008000;"> output: null</span>
    <span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}
</span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$n2</span> == <span style="color: #0000ff;">null</span><span style="color: #000000;">)
{
    </span><span style="color: #0000ff;">echo</span> "null"; <span style="color: #008000;">//</span><span style="color: #008000;"> output: null</span>
    <span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
}


</span><span style="color: #008000;">/*</span><span style="color: #008000;">
 * 数据类型间的显示转换
 * (int)
 * (bool)
 * (float)
 * (string)
 * (array)
 * (object)
 </span><span style="color: #008000;">*/</span>

<span style="color: #008000;">//</span><span style="color: #008000;"> 数据类型间的隐式转换</span>
<span style="color: #800080;">$v</span> = "1"; <span style="color: #008000;">//</span><span style="color: #008000;"> 字符串类型</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$v</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;">$v</span> = 2 + <span style="color: #800080;">$v</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> 隐式转换为整型</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$v</span>; <span style="color: #008000;">//</span><span style="color: #008000;"> output: 3</span>
<span style="color: #0000ff;">echo</span> "<br>";

2、数据类型: array
basic/type2.php

<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
 * 数据类型: array
 </span><span style="color: #008000;">*/</span>

<span style="color: #008000;">//</span><span style="color: #008000;"> 定义数组（数组中的 key 索引为从 0 开始的递增的整型）</span>
<span style="color: #800080;">$array0</span> = <span style="color: #0000ff;">array</span>(1, 2, 3, 4<span style="color: #000000;">);
</span><span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array0</span><span style="color: #000000;">);

</span><span style="color: #008000;">//</span><span style="color: #008000;"> 定义数组</span>
<span style="color: #800080;">$array1</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">
(
    </span>"a" => "abx",
    "x" => "xyz",<span style="color: #000000;">
);
</span><span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array1</span><span style="color: #000000;">);

</span><span style="color: #008000;">//</span><span style="color: #008000;"> 在 php 5.4 之后可以通过 [] 定义数组</span>
<span style="color: #800080;">$array2</span> =<span style="color: #000000;">
[
    </span>"a" => "abx",
    "x" => "xyz",<span style="color: #000000;">
];
</span><span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array2</span><span style="color: #000000;">);

</span><span style="color: #008000;">//</span><span style="color: #008000;"> key 是 integer 类型或 string 类型，如果是其他类型的话会被自动转换为 integer 类型或 string 类型
// key 可以 integer 和 string 两种类型混合存在
// key 为可选项，如果未指定的话，则 PHP 将自动使用之前用过的最大 integer 键名加上 1 作为新的键名，如果没有则从 0 开始</span>
<span style="color: #800080;">$array3</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">
(
    </span>"a" => "abc",
    "x" => "xyz",
    100 => "111",
    100.99 => "222",
    1 => "333",
    <span style="color: #0000ff;">true</span> => "444",
    "a",
    "b",
    "c"<span style="color: #000000;">
);
</span><span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array3</span><span style="color: #000000;">);
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
 * 上面数组定义的结果如下：
 * 'a' => string 'abc'
 * 'x' => string 'xyz'
 * 100 => string '222'
 * 1 => string '444'
 * 101 => string 'a'
 * 102 => string 'b'
 * 103 => string 'c'
 </span><span style="color: #008000;">*/</span>

<span style="color: #008000;">//</span><span style="color: #008000;"> 通过 [] 指定数组字符串类型的 key 并获取其值</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>["a"]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: abc</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 {} 指定数组字符串类型的 key 并获取其值</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>{"a"}; <span style="color: #008000;">//</span><span style="color: #008000;"> output: abc</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 [] 指定数组整型类型的 key 并获取其值（注：这里不是指位置 100 的元素，而是指 key 为 100 的元素）</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>[100]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: 222</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 {} 指定数组整型类型的 key 并获取其值（注：这里不是指位置 100 的元素，而是指 key 为 100 的元素）</span>
<span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>{100}; <span style="color: #008000;">//</span><span style="color: #008000;"> output: 222</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;

</span><span style="color: #008000;">//</span><span style="color: #008000;"> 修改数组中指定 key 的值</span>
<span style="color: #800080;">$array3</span>["a"] = "aaa"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>["a"]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: aaa</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 key 和 value 为数组添加新元素（在数据最后一个元素的后面添加）</span>
<span style="color: #800080;">$array3</span>[50] = "d"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>[50]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: d</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 仅通过 value 为数组添加新元素（在数据最后一个元素的后面添加），key 值将自动使用之前用过的最大 integer 键名加上 1 作为新的键名，如果没有则从 0 开始</span>
<span style="color: #800080;">$array3</span>[] = "e"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>[104]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: e</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;


</span><span style="color: #008000;">//</span><span style="color: #008000;"> 遍历数组</span>
<span style="color: #0000ff;">foreach</span> (<span style="color: #800080;">$array3</span> <span style="color: #0000ff;">as</span> <span style="color: #800080;">$i</span> => <span style="color: #800080;">$value</span><span style="color: #000000;">)
{
    </span><span style="color: #008000;">//</span><span style="color: #008000;"> 销毁数组中的指定元素</span>
    <span style="color: #0000ff;">unset</span>(<span style="color: #800080;">$array3</span>[<span style="color: #800080;">$i</span><span style="color: #000000;">]);
}
</span><span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array3</span><span style="color: #000000;">);
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 之前通过 unset 销毁了每个数组元素，但是数组内部的 key 索引不会被破坏，如下例，其 key 值会由系统分配为 105</span>
<span style="color: #800080;">$array3</span>[] = "xxx"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>[105]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: xxx</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;

</span><span style="color: #008000;">//</span><span style="color: #008000;"> 销毁指定的变量，如果是销毁数组的话，则数组内部的 key 索引也会被破坏</span>
<span style="color: #0000ff;">unset</span>(<span style="color: #800080;">$array3</span><span style="color: #000000;">);
</span><span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array3</span><span style="color: #000000;">);
</span><span style="color: #008000;">//</span><span style="color: #008000;"> 由于之前数组内部的 key 索引被破坏了，所以下例中，其 key 值会由系统分配为 0</span>
<span style="color: #800080;">$array3</span>[] = "yyy"<span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array3</span>[0]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: yyy</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;


</span><span style="color: #008000;">//</span><span style="color: #008000;"> 将任意变量转换为数组时，数组的第一个元素即为该变量本身</span>
<span style="color: #800080;">$s</span> = "sss"<span style="color: #000000;">;
</span><span style="color: #800080;">$array4</span> = (<span style="color: #0000ff;">array</span>)<span style="color: #800080;">$s</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$array4</span>[0]; <span style="color: #008000;">//</span><span style="color: #008000;"> output: sss</span>
<span style="color: #0000ff;">echo</span> "<br>"<span style="color: #000000;">;


</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 array_values 可以重建数组内部的 key 索引</span>
<span style="color: #800080;">$array5</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">
(
    </span>"a" => "abx",
    "x" => "xyz",
    0 => "123",<span style="color: #000000;">
);
</span><span style="color: #800080;">$array5</span> = <span style="color: #008080;">array_values</span>(<span style="color: #800080;">$array5</span>); <span style="color: #008000;">//</span><span style="color: #008000;"> 无论之前的 key 是什么，在 array_values 之后，数组内的 key 索引都将变为从 0 开始递增的整型数据</span>
<span style="color: #008080;">var_dump</span>(<span style="color: #800080;">$array5</span><span style="color: #000000;">);


</span><span style="color: #008000;">//</span><span style="color: #008000;"> 通过 list 函数将数组中的成员依次赋值给指定的变量
// 注意：array[0] 对应 list 的 1 个参数，array[1] 对应 list 的 2 个参数......（这里的 array[0], array[1] 不是指第 0 个元素, 第 1 个元素，而是 key 为 0 的元素, key 为 1 的元素）</span>
<span style="color: #0000ff;">list</span> (<span style="color: #800080;">$r1</span>, <span style="color: #800080;">$r2</span>, <span style="color: #800080;">$r3</span>) = <span style="color: #800080;">$array5</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">echo</span> "<span style="color: #800080;">$r1</span>, <span style="color: #800080;">$r2</span>, <span style="color: #800080;">$r3</span>"; <span style="color: #008000;">//</span><span style="color: #008000;"> output: abx, xyz, 123</span>
<span style="color: #0000ff;">echo</span> "<br>";

OK
[源码下载]