逻辑||(OR) 运算符 无法正常工作.|| 运算符的计算结果始终为布尔值 TRUE 或 FALSE.因此，在您的示例中，您的字符串被转换为布尔值，然后进行比较.

The logical ||(OR) operator doesn't work as you expect it to work. The || operator always evaluates to a boolean either TRUE or FALSE. So in your example your strings get converted into booleans and then compared.

If 语句:

if($ext == ('txt' || 'rtf'|| 'log' || 'docx'))

归结为:

if($ext == (TRUE || TRUE || TRUE || TRUE))
if($ext == TRUE)

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要解决这个问题并使代码按照您的意愿工作，您可以使用不同的方法.

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To solve this problem and get the code to work as you want it to you can use different methods.

解决问题并根据多个值检查您的值的一种方法是，实际将值与多个值进行比较:

One way to solve the problem and check your values against multiple values is, to actually compare the value against multiple values:

if($ext == "txt" || $ext == "rtf" /* || ... */)

in_array()

另一种方法是使用函数 in_array() 并检查该值是否等于数组值之一:

in_array()

Another way is to use the function in_array() and check if the value is equal to one of the array values:

if(in_array($ext, ["txt", "rtf" /* , ... */], TRUE))

_{注意:第二个参数用于严格比较}

您也可以使用 switch 来根据多个值检查您的值，然后让案例失败.

You could also use switch to check your value against multiple values and just let the case fall through.

switch($ext){

    case "txt":
    case "rtf":
 /* case ...: */
        $pClass = "text-";
    break;

}