C# If string is not null or empty else 一个衬里
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One liner for If string is not null or empty else
提问by user2140261
I usually use something like this for various reasons throughout an application:
我通常在整个应用程序中出于各种原因使用这样的东西：
if (String.IsNullOrEmpty(strFoo))
{
FooTextBox.Text = "0";
}
else
{
FooTextBox.Text = strFoo;
}
If I'm going to be using it a lot I will create a method that returns the desired string. For example:
如果我要经常使用它，我将创建一个返回所需字符串的方法。例如：
public string NonBlankValueOf(string strTestString)
{
if (String.IsNullOrEmpty(strTestString))
return "0";
else
return strTestString;
}
and use it like:
并使用它：
FooTextBox.Text = NonBlankValueOf(strFoo);
I always wondered if there was something that was part of C# that would do this for me. Something that could be called like:
我一直想知道是否有 C# 的一部分可以为我做这件事。可以这样称呼的东西：
FooTextBox.Text = String.IsNullOrEmpty(strFoo,"0")
the second parameter being the returned value if String.IsNullOrEmpty(strFoo) == true
第二个参数是返回值，如果 String.IsNullOrEmpty(strFoo) == true
If not does anyone have any better approaches they use?
如果没有，有没有人有更好的方法？
采纳答案by Anthony Pegram
There is a null coalescing operator (??), but it would not handle empty strings.
有一个空合并运算符 ( ??)，但它不会处理空字符串。
If you were only interested in dealing with null strings, you would use it like
如果你只对处理空字符串感兴趣，你会像这样使用它
string output = somePossiblyNullString ?? "0";
For your need specifically, there is simply the conditional operator bool expr ? true_value : false_valuethat you can use to simply if/else statement blocks that set or return a value.
根据您的具体需要bool expr ? true_value : false_value，您可以使用简单的条件运算符来简单地设置或返回值的 if/else 语句块。
string output = string.IsNullOrEmpty(someString) ? "0" : someString;
回答by Hossein Narimani Rad
This may help:
这可能有帮助：
public string NonBlankValueOf(string strTestString)
{
return String.IsNullOrEmpty(strTestString)? "0": strTestString;
}
回答by Jim Mischel
You could use the ternary operator:
您可以使用三元运算符：
return string.IsNullOrEmpty(strTestString) ? "0" : strTestString
FooTextBox.Text = string.IsNullOrEmpty(strFoo) ? "0" : strFoo;
回答by ssilas777
You can write your own Extensionmethod for type String :-
您可以为 String 类型编写自己的扩展方法：-
public static string NonBlankValueOf(this string source)
{
return (string.IsNullOrEmpty(source)) ? "0" : source;
}
Now you can use it like with any string type
现在您可以像使用任何字符串类型一样使用它
FooTextBox.Text = strFoo.NonBlankValueOf();
回答by dathompson
Old question, but thought I'd add this to help out,
老问题，但我想我会添加这个来帮助，
#if DOTNET35
bool isTrulyEmpty = String.IsNullOrEmpty(s) || s.Trim().Length == 0;
#else
bool isTrulyEmpty = String.IsNullOrWhiteSpace(s) ;
#endif
