VB to C# Functions

UBound()  "array".Length
LBound()
IsNothing(): "object" == null
Chr()     (char)"N"
Len()     "string".Length
UCase()   "string".ToUpper()
LCase()   "string".ToLower()
Left()    "string".Substring(from, to)
Right()   "string".Substring(from, to)
RTrim()   "string".TrimEnd()
LTrim()   "string".TrimStart()
Trim()    "string".Trim()
Mid()     "string".Substring(from, to)
Replace() "string".Replace()
Split()   "string".Split()
Join()    String.Join()
MsgBox()  MessageBox.Show()
IIF()     validate ? iftrue : iffalse;

All these functions are member methods of the Microsoft.VisualBasic.Information class, in the Microsoft.VisualBasic assembly, so you can use them directly. However, most of them have C# equivalents, or non language specific equivalents in core .NET framework classes :

• UBound() : Array.GetUpperBound
• LBound() : Array.GetLowerBound
• IsNothing() : == null
• Chr() : (char)intValue (cast)
• Len() : String.Length
• UCase() : String.ToUpper
• LCase() : String.ToLower
• Left(), Right() and Mid() : String.Substring (with different arguments)
• RTrim() : String.TrimEnd
• LTrim() : String.TrimStart
• Trim() : String.Trim
• Replace() : String.Replace
• Split() : String.Split
• Join() : String.Join
• MsgBox() : MessageBox.Show
• IIF() : condition ? valueIfTrue : valueIfFalse (conditional operator)

Links

• Array members
• String members
• MessageBox.Show
• conditional operator

Most of these would be instance methods on the string object that return the modified string.

MsgBox vs. MessageBox.Show(..)

IIF vs. (expression?returnValueIfTrue:returnValueElse)

IIf(test, trueval, falseval) >> (test ? trueval : falseval);

IsNothing(obj) >> (obj == null);

UCase(str) >> str.ToUpper();

LCase(str) >> str.ToLower();

First of all, most of those are NOT operators. They are functions, and the functions are only included in VB.Net for compatibility reasons. That means you shouldn't use them in VB.net either, and instead use the equivalents provided by the new API.

• UBound() — arrayVar.Length
• LBound() — obsolete, lower bound is always 0 in a normal .Net array
• IsNothing() — obsolete. Use Is Nothing in VB.Net and == null in C#
• Chr() — Convert.ToChar() or (char)someVar
• Len() — stringVar.Length use this in VB too
• UCase() — stringVar.ToUpper() use this in VB too
• LCase() — stringVar.ToLower() use this in VB too
• Left() — stringVar.Substring(0, n) use this in VB too
• Right() — stringVar.Substring(stringVar.Length - n) use this in VB too
• RTrim() — stringVar.TrimEnd() use this in VB too
• LTrim() — stringVar.TrimStart() use this in VB too
• Trim() — stringVar.Trim() use this in VB too
• Mid() — stringVar.Substring(n, m) use this in VB too
• Replace() — stringVar.Replace() use this in VB too
• Split() — stringVar.Split() use this in VB too
• Join() — String.Join() use this in VB too
• MsgBox() — MessageBox.Show()
• IIF() — (condition) ? truepart : falsepart - note that there are some differences, because "?" is an operator and not a function

You'll find the conversion for many of these functions on this wikipedia page.

I believe some of these like Mid() are still available in the .NET Framework in the Microsoft.VisualBasic namespace which you can still reference from C# code.

Another one...

VB - IsDBNull(value)

C# - yourdatarow.IsNull("columnName")

In addition to the answers above. Be carefull with replacing Len() -> x.Length. VB Len() allows you to pass null, but in c# you will get an exception. Sometimes it would be better to use String.IsNullrEmpty() (If the situation allows)

If you look on MSDN you see that most of the time there are sample code for both languages.

• UBound() -> if x is an array of string[] for example: x.GetUpperBound();
• LBound() -> if x is an array of string[] for example: x.GetLowerBound();
• IsNothing() -> if (x == null)
• Chr() -> char x = (char)65;
• Len() -> x.Length();
• UCase() -> assume x is a string: x.ToUpper();
• LCase() -> assume x is a string: x.ToLower();
• Left() -> assume x is a string: x.Substring(0, 10); // first 10 characters
• Right() -> assume x is a string: x.Substring(x.Length - 10); // last 10 characters
• RTrim() -> x.TrimEnd();
• LTrim() -> x.TrimStart();
• Trim() -> x.Trim();
• Mid() -> assume x is a string: x.Substring()
• Replace() -> assume x is a string: x.Replace();
• Split() -> assume x is a string: x.Split();
• Join() -> String.Join();
• MsgBox() -> MessageBox.Show();
• IIF() -> ternary operator (x == true ? true-value : false-value);

One more addition to this could be IndexOf() function to Find String within string

An example below...

string MainString = "String Manipulation"; 
string SearchString = "pul"; 
int FirstChr = MainString.IndexOf(SearchString); 
//SHOWS START POSITION OF STRING 
MessageBox.Show("Found at : " + FirstChr );

The space function is missing from everyone else's list:

Space(16) -> new String(" ", 16)