VB 到 C# 函数

问题描述

以下从 VB.Net 到 C# 的运算符有哪些等价的?

Which are the equivalent of the following operators from VB.Net to C#?

• UBound()
• LBound()
• IsNothing()
• Chr()
• Len()
• UCase()
• LCase()
• 左()
• 右()
• RTrim()
• LTrim()
• 修剪()
• 中()
• 替换()
• 拆分()
• 加入()
• MsgBox()
• IIF()

推荐答案

VB             C#

UBound()     = yourArray.GetUpperBound(0) or yourArray.Length for one-dimesional arrays
LBound()     = yourArray.GetLowerBound(0)
IsNothing()  = Object.ReferenceEquals(obj,null)
Chr()        = Convert.ToChar()
Len()        = "string".Length
UCase()      = "string".ToUpper()
LCase()      = "string".ToLower()
Left()       = "string".Substring(0, length)
Right()      = "string".Substring("string".Length - desiredLength)
RTrim()      = "string".TrimEnd()
LTrim()      = "string".TrimStart()
Trim()       = "string".Trim()
Mid()        = "string".Substring(start, length)
Replace()    = "string".Replace()
Split()      = "string".Split()
Join()       = String.Join()
MsgBox()     = MessageBox.Show()
IIF()        = (boolean_condition ? "true" : "false")

注意事项

• yourArray.GetUpperBound(0) vs yourArray.Length:如果数组的长度为零，GetUpperBound 将返回 -1，而 Length 将返回 0.UBound() 将为零长度数组返回 -1.
• VB 字符串函数使用基于 1 的索引，而 .NET 方法使用基于 0 的索引.IE.Mid("asdf",2,2) 对应于"asdf".SubString(1,2).
• ? 不是 IIf 的完全等价物，因为 IIf 总是计算 both 参数和 ? 只评估它需要的那个.如果评估有副作用，这可能很重要~不寒而栗！
• 许多经典的VB字符串函数，包括Len()、UCase()、LCase()、Right()、RTrim() 和 Trim() 将处理 Nothing (Null在 c# 中)相当于零长度的字符串.在 Nothing 上运行字符串方法当然会抛出异常.
• 您还可以将 Nothing 传递给经典的 VB Mid() 和 Replace() 函数.这些不会抛出异常，而是返回 Nothing.

• yourArray.GetUpperBound(0) vs yourArray.Length: if the array is zero-length, GetUpperBound will return -1, while Length will return 0. UBound() in VB.NET will return -1 for zero-length arrays.
• The VB string functions uses a one based index, while the .NET method uses a zero based index. I.e. Mid("asdf",2,2) corresponds to "asdf".SubString(1,2).
• ? is not the exact equivalent of IIf because IIf always evaluates both arguments, and ? only evaluates the one it needs. This could matter if there are side effects of the evaluation ~ shudder!
• The Many classic VB String functions, including Len(), UCase(), LCase(), Right(), RTrim(), and Trim(), will treat an argument of Nothing (Null in c#) as being equivalent to a zero-length string. Running string methods on Nothing will, of course, throw an exception.
• You can also pass Nothing to the classic VB Mid() and Replace() functions. Instead of throwing an exception, these will return Nothing.

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