Powershell - 我如何在我的數組中計數發生次數

Question

因此，我將讀主機的輸入數據轉換爲一個數組，我想它可以讓我計算句子$ a中的單詞從$陣列。然而伯爵++不給我一個總

function Get-Sentence($a){ 
       if($a -contains $array) { 
        $Count++ 
       } 
      else { 
        return 0 
       } 
     } 
     Write-Host "There are $count words" 

     [array]$Array = @("a", "an", "the") 
     [array]$a = Read-Host "Enter a long sentence from a story book or novel: ").split(" ") 

Answer 1

首選的方法：

最簡單的方式準確地計算多子的出現大概是：

上的任何一個匹配

1. 構建正則表達式模式子字符串
2. 使用-split運算符分割字符串
3. 計算字符串的結果數量和。減去1：

---

# Define the substrings and a sentence to test against 
$Substrings = "a","an","the" 
$Sentence = "a long long sentence to test the -split approach, anticipating false positives" 

# Construct the regex pattern 
# The \b sequence ensures "word boundaries" on either side of a 
# match so that "a" wont match the a in "man" for example 
$Pattern = "\b(?:{0})\b" -f ($Substrings -join '|') 

# Split the string, count result and subtract 1 
$Count = ($Sentence -split $Pattern).Count - 1 

輸出：

C:\> $Count 
2 

正如你可以看到它已經匹配和拆分 「」 和 「」，而不是 「一個」 在上「期待」。

我會離開的運動轉換成該功能向讀者

---

注： 如果你開始喂不僅僅是簡單的ASCII字符串作爲輸入更多的，你可能需要之前逃離他們利用它們在模式：

$Pattern = "\b(?:{0})\b" -f (($Substrings |ForEach-Object {[regex]::Escape($_)}) -join '|') 

---

原始的方法：

如果您對正則表達式感到不舒服，您可以假定兩個空格之間的任何內容都是「一個單詞」（就像在您的原始示例中一樣），然後遍歷句子中的單詞並檢查是否爲陣列包含問題的字（而不是其他方式）：

$Substrings = "a","an","the" 
$Sentence = (Read-Host "Enter a long sentence from a story book or novel: ").Split(" ") 

$Counter = 0 

foreach($Word in $Sentence){ 
    if($Substrings -contains $Word){ 
     $Counter++ 
    } 
} 

---

由於suggested by Jeroen Mostert，你也可以利用哈希表。有了這個，你可以跟蹤每個單詞的出現，而不只是一個總數：

$Substrings = "a","an","the" 
$Sentence = (Read-Host "Enter a long sentence from a story book or novel: ").Split(" ") 

# Create hashtable from substrings 
$Dictionary = @{} 
$Substrings |ForEach-Object { $Dictionary[$_] = 0 } 

foreach($Word in $Sentence){ 
    if($Dictionary.ContainsKey($Word)){ 
     $Dictionary[$Word]++ 
    } 
} 

$Dictionary 

Answer 2

$Substrings = "a","an","the" 
    ("a long long sentence to test the -split approach, anticipating false positives" -split " " | where {$Substrings -contains $_}).Count