C# 返回空数组而不是null

我创建了

Settings

类，用于通过

.ini

文件编辑我的应用程序。我的

Settings.ini

文件如下所示：

[ACCOUNT]
login=xyz
password=xyz
locations=1,2,5,8

class Settings {
    public static IniFile Config = new IniFile(Directory.GetCurrentDirectory() + @"\Settings.ini");
    public static string Login { get { return Config.Read("login", "ACCOUNT"); } set { Config.Write("login", "ACCOUNT"); } }
    public static string Password { get { return Config.Read("password", "ACCOUNT"); } set { Config.Write("password", "ACCOUNT"); } }
    public static int[] Locations { get { return Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s)); } set { Config.Write("locations", "ACCOUNT"); } }
}

public static int[] Locations 
{ 
    get { return new int[] {Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s))}; } 
    set { Config.Write("locations", "ACCOUNT"); } 
}

public static int[] Locations 
{ 
    get 
    { 
        int[] values = Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), 
            s => int.Parse(s)) ?? new int[] { };
        return values; 
    } 
    set 
    { 
        Config.Write("locations", "ACCOUNT"); 
    } 
}

public static int[] Locations
{
    get
    {
        string locations = Config.Read("locations", "ACCOUNT");
        if (locations == null)
        {
            return new int[0];
        }
        return locations
                .Split(',')         // split the locations separated by a comma
                .Select(int.Parse)  // transform each string into the corresponding integer
                .ToArray();         // put the resulting sequence (IEnumerable<int>) into an array of integers
    }
    set
    {
        Config.Write("locations", "ACCOUNT");
    }
}

现在我得到了如下这些值：

[ACCOUNT]
login=xyz
password=xyz
locations=1,2,5,8

class Settings {
    public static IniFile Config = new IniFile(Directory.GetCurrentDirectory() + @"\Settings.ini");
    public static string Login { get { return Config.Read("login", "ACCOUNT"); } set { Config.Write("login", "ACCOUNT"); } }
    public static string Password { get { return Config.Read("password", "ACCOUNT"); } set { Config.Write("password", "ACCOUNT"); } }
    public static int[] Locations { get { return Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s)); } set { Config.Write("locations", "ACCOUNT"); } }
}

public static int[] Locations 
{ 
    get { return new int[] {Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s))}; } 
    set { Config.Write("locations", "ACCOUNT"); } 
}

public static int[] Locations 
{ 
    get 
    { 
        int[] values = Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), 
            s => int.Parse(s)) ?? new int[] { };
        return values; 
    } 
    set 
    { 
        Config.Write("locations", "ACCOUNT"); 
    } 
}

public static int[] Locations
{
    get
    {
        string locations = Config.Read("locations", "ACCOUNT");
        if (locations == null)
        {
            return new int[0];
        }
        return locations
                .Split(',')         // split the locations separated by a comma
                .Select(int.Parse)  // transform each string into the corresponding integer
                .ToArray();         // put the resulting sequence (IEnumerable<int>) into an array of integers
    }
    set
    {
        Config.Write("locations", "ACCOUNT");
    }
}

问题是，当我的

Settings.ini

文件的位置为空时：

locations=

我的变量

Settings.Locations

返回

null

而不是空数组。我试过这样做：

[ACCOUNT]
login=xyz
password=xyz
locations=1,2,5,8

class Settings {
    public static IniFile Config = new IniFile(Directory.GetCurrentDirectory() + @"\Settings.ini");
    public static string Login { get { return Config.Read("login", "ACCOUNT"); } set { Config.Write("login", "ACCOUNT"); } }
    public static string Password { get { return Config.Read("password", "ACCOUNT"); } set { Config.Write("password", "ACCOUNT"); } }
    public static int[] Locations { get { return Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s)); } set { Config.Write("locations", "ACCOUNT"); } }
}

public static int[] Locations 
{ 
    get { return new int[] {Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s))}; } 
    set { Config.Write("locations", "ACCOUNT"); } 
}

public static int[] Locations 
{ 
    get 
    { 
        int[] values = Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), 
            s => int.Parse(s)) ?? new int[] { };
        return values; 
    } 
    set 
    { 
        Config.Write("locations", "ACCOUNT"); 
    } 
}

public static int[] Locations
{
    get
    {
        string locations = Config.Read("locations", "ACCOUNT");
        if (locations == null)
        {
            return new int[0];
        }
        return locations
                .Split(',')         // split the locations separated by a comma
                .Select(int.Parse)  // transform each string into the corresponding integer
                .ToArray();         // put the resulting sequence (IEnumerable<int>) into an array of integers
    }
    set
    {
        Config.Write("locations", "ACCOUNT");
    }
}

---

但这是行不通的。我无法将int[]转换为int。您知道如何返回空数组吗？

首先，您在一行中插入的内容太多，因此很难读取，更不用说故障排除了。你需要的是这样的东西：

[ACCOUNT]
login=xyz
password=xyz
locations=1,2,5,8

class Settings {
    public static IniFile Config = new IniFile(Directory.GetCurrentDirectory() + @"\Settings.ini");
    public static string Login { get { return Config.Read("login", "ACCOUNT"); } set { Config.Write("login", "ACCOUNT"); } }
    public static string Password { get { return Config.Read("password", "ACCOUNT"); } set { Config.Write("password", "ACCOUNT"); } }
    public static int[] Locations { get { return Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s)); } set { Config.Write("locations", "ACCOUNT"); } }
}

public static int[] Locations 
{ 
    get { return new int[] {Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s))}; } 
    set { Config.Write("locations", "ACCOUNT"); } 
}

public static int[] Locations 
{ 
    get 
    { 
        int[] values = Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), 
            s => int.Parse(s)) ?? new int[] { };
        return values; 
    } 
    set 
    { 
        Config.Write("locations", "ACCOUNT"); 
    } 
}

public static int[] Locations
{
    get
    {
        string locations = Config.Read("locations", "ACCOUNT");
        if (locations == null)
        {
            return new int[0];
        }
        return locations
                .Split(',')         // split the locations separated by a comma
                .Select(int.Parse)  // transform each string into the corresponding integer
                .ToArray();         // put the resulting sequence (IEnumerable<int>) into an array of integers
    }
    set
    {
        Config.Write("locations", "ACCOUNT");
    }
}

注意，我添加了

？？在调用的第一条语句末尾添加新的int[]{}

。如果另一个数组为null，它将返回一个空数组

---

这是一个偏好的问题，但我将getter分成两行的原因是，我可以在它返回之前进行调试和中断，以观察返回值。您也可以在最后一个括号中打断，并在“局部变量”窗口中观察返回值。

您可以这样显式执行：

[ACCOUNT]
login=xyz
password=xyz
locations=1,2,5,8

class Settings {
    public static IniFile Config = new IniFile(Directory.GetCurrentDirectory() + @"\Settings.ini");
    public static string Login { get { return Config.Read("login", "ACCOUNT"); } set { Config.Write("login", "ACCOUNT"); } }
    public static string Password { get { return Config.Read("password", "ACCOUNT"); } set { Config.Write("password", "ACCOUNT"); } }
    public static int[] Locations { get { return Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s)); } set { Config.Write("locations", "ACCOUNT"); } }
}

public static int[] Locations 
{ 
    get { return new int[] {Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s))}; } 
    set { Config.Write("locations", "ACCOUNT"); } 
}

public static int[] Locations 
{ 
    get 
    { 
        int[] values = Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), 
            s => int.Parse(s)) ?? new int[] { };
        return values; 
    } 
    set 
    { 
        Config.Write("locations", "ACCOUNT"); 
    } 
}

public static int[] Locations
{
    get
    {
        string locations = Config.Read("locations", "ACCOUNT");
        if (locations == null)
        {
            return new int[0];
        }
        return locations
                .Split(',')         // split the locations separated by a comma
                .Select(int.Parse)  // transform each string into the corresponding integer
                .ToArray();         // put the resulting sequence (IEnumerable<int>) into an array of integers
    }
    set
    {
        Config.Write("locations", "ACCOUNT");
    }
}

公共静态int[]位置
{
得到
{
字符串位置=Config.Read（“位置”、“帐户”）；
如果（位置==null）
{
返回新整数[0]；
}
返回位置
.Split（“，”）//分割用逗号分隔的位置
.Select（int.Parse）//将每个字符串转换为相应的整数
.ToArray（）；//将结果序列（IEnumerable）放入整数数组中
}
设置
{
配置写入（“位置”、“账户”）；
}
}

为什么要声明值而不使用它？除了缺少的

我收到了
格式异常
，但我没有注意到。您的代码也不能正常工作。我不明白，
Config.Read（“位置”，“帐户”）
如果没有位置，则返回null？因为
Locations
属性从不返回null，因为
Array.ConvertAll
从不返回null。但是如果
Config.Read
返回null
string，Split
将抛出异常。你是对的。现在我注意到我得到的是
格式异常
而不是
数组。ConvertAll
您应该使用循环和
int.TryParse
来尝试解析每个标记。然后，您可以处理无效的输入。我必须更改为：
if（string.IsNullOrEmpty（works））{
并且它工作得很好。谢谢：）VS现在对此的抱怨。它建议
Array.Empty（）；
。