ConvertFromString不返回默认null [英] ConvertFromString not returning default null

问题描述

为什么以下代码返回一个空字符串而不是null?

Why does the following code return an empty string and not null?

TypeConverter typeConverter = TypeDescriptor.GetConverter(typeof(String));
typeConverter.ConvertFromString(null);

当 Microsoft文档指出默认实现始终返回null时.

When the Microsoft documentation remarks that the default implementation always returns null.

推荐答案

TypeConverter typeConverter = TypeDescriptor.GetConverter(typeof(string));
typeConverter.CanConvertFrom(null); //返回"false"的地方表示不可转换
typeConverter.ConvertFromString(null);


还需要字符串参数作为输入-> http://msdn.microsoft.com/zh-CN/library/25ds5cb6.aspx
并且string的默认值为String.Empty，它仍在挖掘问题，并将在此处提出更多的事实...

TypeConverter typeConverter = TypeDescriptor.GetConverter(typeof(string));
typeConverter.CanConvertFrom(null); //where it return "false" means not convertable
typeConverter.ConvertFromString(null);


also it required string parameter as input-> http://msdn.microsoft.com/en-us/library/25ds5cb6.aspx
and the default value of string is String.Empty, still digging the issue and will come up with more facts over here...

public Object ConvertFromString(
    string text
)

Parameters
textType: System.String

The text representation of the object to convert.


Return Value
Type: System.Object
An Object that represents the converted text.

也请尝试以下代码块及其返回的预期结果:

also try this block of code and its returning desired outcome:

public Object ConvertFromString(string text)
{
    return text;
}

ConvertFromString("test string"); //return "test string"
ConvertFromString(string.Empty); // return ""
ConvertFromString(null); // return null

请问我需要相同的任何内容.

Ask me if required any specific in same..

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