Question

我有一个变量，它总是包含以下两种情况之一：

'date can be in any form and this method worked for either US or UK locale 'this method always solve the problem of date settings e.g 9/24/2016 or 09/24/2016 Dim age as string = "07/30/2010" 'age Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "MM-dd-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex As Exception Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "M-dd-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex2 As Exception Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "M-d-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex3 As Exception Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "MM-d-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex4 As Exception Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "dd-MM-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex5 As Exception Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "dd-M-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex6 As Exception Try Dim birthDate = Date.ParseExact(age.replace("/", "-"), "d-M-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") Catch ex7 As Exception Dim birthDate = Date.ParseExact(age.replace("/", "-"), "d-MM-yyyy", Nothing) Return (Math.Floor(Date.Now.Subtract(birthDate).TotalDays / 365) & " yrs") End Try End Try End Try End Try End Try End Try End Try
一个数字（也可以是false）

我的变量实际上是这样的：

现在我想检测$index = array_search(1, array_column($var, 'box')); //=> the output could be something like these: false, 0, 1, 2, ...是$index还是其他任何内容。我怎样才能实现这样的条件？

应该注意的是，这些都不起作用：

false

我想要这个条件：

if ( empty($index) )   { }
if ( !isset($index) )  { }
if ( is_null($index) ) { }

Answer 1

使用===运算符...

if(false == 0)

那会将0转为false而你会得到false == false

if(false === 0)

与零相比，这不会被施放，你会得到假，这是不一样的。

如果不等于，请使用！==而不是===

Answer 2

您可以使用PHP相同的运算符===：

if (false === 0)

如果它们属于同一类型，则返回false。与发生类型杂耍的==不同，false与0不同。

if ($index === false) { 
    // $index is false
} else {
    // $index is a number (even 0)
}

有关相同运算符===与比较运算符==之间差异的详细信息：How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?

如何确定false和0之间的差异？

2 个答案: