# 固定長のShift_JISファイルの特定位置の文字を削除する
$filename = "hogehoge.txt"
$tempfile = "ZZZZZ_$filename"
$enc = [Text.Encoding]::GetEncoding("Shift_JIS")
$fhIn = New-Object System.IO.StreamReader($filename, $enc)
$fhOut = New-Object System.IO.StreamWriter($tempfile, $false, $enc)
$isCuted = $FALSE

# 1行ずつ処理
while (($l = $fhIn.ReadLine()) -ne $null) {
    # 1文字ずつ処理
    $tmpString = [System.Linq.Enumerable]::ToArray($l)

    if($enc.GetByteCount($l) -le 760) {
        Write-Host "すでに加工済みです"
        $isCuted = $TRUE
        break
    }

    $iCount = 0
    $sOutLine = ""
    foreach($tmpChar in $tmpString) {
        $iCount = $iCount + $enc.GetByteCount($tmpChar)

        # 特定位置の文字を処理しない
        switch($iCount) {
            {$_ -le 550} {$sOutLine = $sOutLine + $tmpChar} # <= 549
            {$_ -ge 552 -band $_ -le 744} {$sOutLine = $sOutLine + $tmpChar} # >= 552 AND <= 744
        }
    }

    $fhOut.WriteLine($sOutLine)
}

$fhIn.Close()
$fhOut.Close()


# ファイル名の変更
if($isCuted -eq $TRUE) {
    Remove-Item $tempfile
} else {
    $nowDate = Get-Date -Format "yyyyMMdd_HHmmss"
    Move-Item $filename "$nowDate-$filename"
    Move-Item $tempfile $filename
}