PowerShell报错“无法索引空数组”求助：数组已预填充仍出错

问题描述 #

脚本第40行的比较操作始终返回“cannot index into a null array”错误。已将数组预填充为0确保非空，且数组长度大于导入的表格，调试输出显示数组已存储值，但错误从循环首次运行时就出现。相关代码如下：

Import-Module -Name ImportExcel

$CurrentFOBDoc = Import-Excel "path\to\doc"

$CurrentElikaFOB = Import-CSV "path\to\doc"

$AuditResluts = [Object[]]::new(300)

$count = 0

foreach($value in $AuditResluts){
    $AuditResluts[$count] = 0
    $count++
}

$count = 0

foreach ($Fob in $CurrentFOBDoc){

    foreach ($EFob in $CurrentElikaFOB){
        IF($Fob.'Card Number' -like $EFob.'Wiegand 1 Code'){

            IF($Fob.'Facility Number' -like $EFob.'Facility 1 Code'){

                If(($Fob.'First Name' -like $EFob.'First Name' ) -and ($Fob.'Last Name' -like $EFob.'Last Name')){

                    $AuditResluts[$count] = "Fob $($Fob.'Facility Number') $($Fob.'Card Number') is assigned to $($Fob.'First Name')  $($Fob.'Last Name') in Elika and Log Sheet"
                                               
                }
                Else{
                    $AuditResults[$count] = "Fob $($Fob.'Facility Number') $($Fob.'Card Number') is not assigned to $($Fob.'First Name') $($Fob.'Last Name') in Elika, please reconcile"
                }
            }
        }
        
    }

    echo $AuditResluts[$count]

   #This Comparison gives the error, -eq gives the same result
    If($AuditResults[$count] -like 0){
        $AuditResults[$count] = "Fob $($Fob.'Facility Number') $($Fob.'Card Number') assigned to $($Fob.'First Name') $($Fob.'Last Name') Not found in Elika"
    }

    $count ++
}

错误原因 #

核心问题是数组变量名拼写不一致：

• 初始化和预填充数组时使用的变量名是$AuditResluts（拼写错误，少了字母u）
• 但在内层循环的Else分支、第40行的判断及后续赋值中，使用的是$AuditResults（正确拼写）

由于$AuditResults从未被初始化，它本质是一个未定义的null变量，当尝试索引$AuditResults[$count]时，自然会抛出“cannot index into a null array”错误。

修复方案 #

将所有数组变量名统一为正确的拼写$AuditResults（或统一为$AuditResluts，建议使用正确拼写避免后续混淆），修正后的代码如下：

Import-Module -Name ImportExcel

$CurrentFOBDoc = Import-Excel "path\to\doc"

$CurrentElikaFOB = Import-CSV "path\to\doc"

# 统一变量名拼写
$AuditResults = [Object[]]::new(300)

$count = 0

foreach($value in $AuditResults){
    $AuditResults[$count] = 0
    $count++
}

$count = 0

foreach ($Fob in $CurrentFOBDoc){

    foreach ($EFob in $CurrentElikaFOB){
        IF($Fob.'Card Number' -like $EFob.'Wiegand 1 Code'){

            IF($Fob.'Facility Number' -like $EFob.'Facility 1 Code'){

                If(($Fob.'First Name' -like $EFob.'First Name' ) -and ($Fob.'Last Name' -like $EFob.'Last Name')){

                    $AuditResults[$count] = "Fob $($Fob.'Facility Number') $($Fob.'Card Number') is assigned to $($Fob.'First Name')  $($Fob.'Last Name') in Elika and Log Sheet"
                                               
                }
                Else{
                    $AuditResults[$count] = "Fob $($Fob.'Facility Number') $($Fob.'Card Number') is not assigned to $($Fob.'First Name') $($Fob.'Last Name') in Elika, please reconcile"
                }
            }
        }
        
    }

    echo $AuditResults[$count]

   # 修正变量名后即可正常比较
    If($AuditResults[$count] -like 0){
        $AuditResults[$count] = "Fob $($Fob.'Facility Number') $($Fob.'Card Number') assigned to $($Fob.'First Name') $($Fob.'Last Name') Not found in Elika"
    }

    $count ++
}

内容的提问来源于stack exchange，提问作者AlexBoBalex