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VB.NET strings are .NET String objects — same as C#. Plus VB-specific functions like Mid, Left, Right (legacy from VB6).

Concatenation

Dim s = "hello" & " " & "world"   ' & is the canonical concat
Dim t = "hello" + " " + "world"   ' + works but ambiguous
s &= "!"                            ' append

Use & — + between two numerics still adds. Mixing types triggers conversions.

Length and indexing

Dim s = "hello"
s.Length                  ' 5
s(0)                      ' "h" (1-char string in VB.NET .NET 4.0+; previously Char)
s.Substring(1, 3)         ' "ell" (start, length)
s.Substring(2)            ' "llo" (from index to end)

Modern .NET methods

s.ToUpper()
s.ToLower()
s.Trim()
s.IndexOf("l")            ' 2
s.Contains("ell")          ' True
s.StartsWith("hello")
s.EndsWith("o")
s.Replace("l", "L")        ' "heLLo"
s.Split(" "c)              ' array of substrings ("c" suffix = Char literal)
String.Join(",", {"a", "b", "c"})    ' "a,b,c"

Legacy VB6-style functions

Still available, mostly for VB6 compatibility:

Mid(s, 2, 3)              ' "ell" (1-indexed!)
Left(s, 3)                 ' "hel"
Right(s, 2)                ' "lo"
Len(s)                     ' 5
UCase(s)                   ' "HELLO"
LCase(s)                   ' "hello"

Beware: Mid is 1-indexed; Substring is 0-indexed. Pick one style and stick with it.

String interpolation

Dim name = "Ada"
Dim age = 36
Dim msg = $"{name} is {age} years old"
' "Ada is 36 years old"

Dim formatted = $"{age:D5}"      ' "00036" — D5 = 5-digit decimal
Dim money = $"{99.5:C}"         ' "$99.50" (locale-dependent)

The $"..." is the same as C#'s string interpolation.

String.Format

Dim msg = String.Format("{0} is {1} years old", name, age)
Dim padded = String.Format("{0,10}", name)            ' right-aligned, 10 chars
Dim leftPadded = String.Format("{0,-10}|", name)      ' left-aligned
Dim formatted = String.Format("{0:N2}", 1234.567)    ' "1,234.57"

Format specifiers: D (decimal), N (number with separators), C (currency), P (percent), F2 (2-decimal float), X (hex).

Constants

• vbCrLf — Windows newline (\r\n)
• vbLf — Unix newline
• vbTab — tab
• vbNullChar — NUL

String builder for performance

Imports System.Text

Dim sb As New StringBuilder()
For i = 1 To 1000
    sb.Append(i.ToString())
    sb.Append(",")
Next
Dim result = sb.ToString()

Much faster than &= in loops — string concat allocates a new string each time.