如何在C#中的條碼操作中處理空值檢查

using IronBarCode;

// BarcodeReader.Read() returns a BarcodeResults collection, not a single result
BarcodeResults results = BarcodeReader.Read("shipping-label.png");

// Null check: image was not recognized as a valid image source
// Empty check: image was valid but contained no detectable barcodes
if (results is null || results.Count == 0)
{
    // Log, return a default, or throw a domain-specific exception
    Console.WriteLine("No barcodes found in the input image.");
    return;
}

// Collection is safe to iterate; each BarcodeResult holds one decoded barcode
foreach (BarcodeResult result in results)
{
    // Guard individual result properties; partial scans or severely
    // damaged barcodes can produce results where .Value is empty or whitespace
    if (string.IsNullOrWhiteSpace(result.Value))
    {
        Console.WriteLine($"Empty value detected for {result.BarcodeType}");
        continue;
    }

    // BarcodeType identifies the symbology (Code128, QRCode, EAN8, etc.)
    Console.WriteLine($"Type: {result.BarcodeType}, Value: {result.Value}");
}

Imports IronBarCode

' BarcodeReader.Read() returns a BarcodeResults collection, not a single result
Dim results As BarcodeResults = BarcodeReader.Read("shipping-label.png")

' Null check: image was not recognized as a valid image source
' Empty check: image was valid but contained no detectable barcodes
If results Is Nothing OrElse results.Count = 0 Then
    ' Log, return a default, or throw a domain-specific exception
    Console.WriteLine("No barcodes found in the input image.")
    Return
End If

' Collection is safe to iterate; each BarcodeResult holds one decoded barcode
For Each result As BarcodeResult In results
    ' Guard individual result properties; partial scans or severely
    ' damaged barcodes can produce results where .Value is empty or whitespace
    If String.IsNullOrWhiteSpace(result.Value) Then
        Console.WriteLine($"Empty value detected for {result.BarcodeType}")
        Continue For
    End If

    ' BarcodeType identifies the symbology (Code128, QRCode, EAN8, etc.)
    Console.WriteLine($"Type: {result.BarcodeType}, Value: {result.Value}")
Next

using IronBarCode;

// ConfidenceThreshold filters low-quality reads before they enter the
// BarcodeResults collection. Reads below the threshold are discarded
// during scanning, not after, so no post-filtering of the collection is needed.
var options = new BarcodeReaderOptions
{
    ConfidenceThreshold = 0.7  // range 0.0 to 1.0; lower values accept weaker signals
};

BarcodeResults results = BarcodeReader.Read("shipping-label.png", options);

// Still check for null and empty even with a threshold applied;
// an image with no barcodes returns an empty collection, not null
if (results is null || results.Count == 0)
{
    Console.WriteLine("No barcodes met the confidence threshold.");
    return;
}

foreach (var result in results)
    Console.WriteLine($"Type: {result.BarcodeType}, Value: {result.Value}");

Imports IronBarCode

' ConfidenceThreshold filters low-quality reads before they enter the
' BarcodeResults collection. Reads below the threshold are discarded
' during scanning, not after, so no post-filtering of the collection is needed.
Dim options As New BarcodeReaderOptions With {
    .ConfidenceThreshold = 0.7  ' range 0.0 to 1.0; lower values accept weaker signals
}

Dim results As BarcodeResults = BarcodeReader.Read("shipping-label.png", options)

' Still check for null and empty even with a threshold applied;
' an image with no barcodes returns an empty collection, not null
If results Is Nothing OrElse results.Count = 0 Then
    Console.WriteLine("No barcodes met the confidence threshold.")
    Return
End If

For Each result In results
    Console.WriteLine($"Type: {result.BarcodeType}, Value: {result.Value}")
Next

using IronBarCode;
using System.Collections.Generic;
using System.Linq;

// Reusable validation helper — consolidates null, empty, value, and
// expected-format checks into a single method. Returns an empty list
// (never null) so callers do not need to null-check the return value.
public static class BarcodeValidator
{
    public static List<BarcodeResult> GetValidResults(
        string imagePath,
        BarcodeEncoding? expectedType = null,
        double confidenceThreshold = 0.7)
    {
        // Apply confidence threshold at scan level via BarcodeReaderOptions
        var options = new BarcodeReaderOptions
        {
            ConfidenceThreshold = confidenceThreshold
        };

        BarcodeResults results = BarcodeReader.Read(imagePath, options);

        // Return empty list instead of null so callers never need to null-check the return value
        if (results is null || results.Count == 0)
            return new List<BarcodeResult>();

        return results
            .Where(r => !string.IsNullOrWhiteSpace(r.Value))           // skip results with empty decoded data
            .Where(r => expectedType == null || r.BarcodeType == expectedType) // null accepts any symbology
            .ToList();
    }
}

// Usage: pass the image path and the symbology you expect
var validated = BarcodeValidator.GetValidResults(
    "warehouse-scan.png",
    expectedType: BarcodeEncoding.Code128,
    confidenceThreshold: 0.7);

if (validated.Count == 0)
{
    // No valid results; log the failure and skip downstream processing
    return;
}

// All results have passed null, empty, type, and confidence checks
foreach (var barcode in validated)
{
    SendToInventorySystem(barcode.Value, barcode.BarcodeType.ToString()); // placeholder for your downstream call
}

Imports IronBarCode
Imports System.Collections.Generic
Imports System.Linq

' Reusable validation helper — consolidates null, empty, value, and
' expected-format checks into a single method. Returns an empty list
' (never null) so callers do not need to null-check the return value.
Public Module BarcodeValidator
    Public Function GetValidResults(
        imagePath As String,
        Optional expectedType As BarcodeEncoding? = Nothing,
        Optional confidenceThreshold As Double = 0.7) As List(Of BarcodeResult)

        ' Apply confidence threshold at scan level via BarcodeReaderOptions
        Dim options As New BarcodeReaderOptions With {
            .ConfidenceThreshold = confidenceThreshold
        }

        Dim results As BarcodeResults = BarcodeReader.Read(imagePath, options)

        ' Return empty list instead of null so callers never need to null-check the return value
        If results Is Nothing OrElse results.Count = 0 Then
            Return New List(Of BarcodeResult)()
        End If

        Return results _
            .Where(Function(r) Not String.IsNullOrWhiteSpace(r.Value)) _          ' skip results with empty decoded data
            .Where(Function(r) expectedType Is Nothing OrElse r.BarcodeType = expectedType) _ ' null accepts any symbology
            .ToList()
    End Function
End Module

' Usage: pass the image path and the symbology you expect
Dim validated = BarcodeValidator.GetValidResults(
    "warehouse-scan.png",
    expectedType:=BarcodeEncoding.Code128,
    confidenceThreshold:=0.7)

If validated.Count = 0 Then
    ' No valid results; log the failure and skip downstream processing
    Return
End If

' All results have passed null, empty, type, and confidence checks
For Each barcode In validated
    SendToInventorySystem(barcode.Value, barcode.BarcodeType.ToString()) ' placeholder for your downstream call
Next barcode