This document is to compare the syntax between the VB.Net and C#.Net for various coding concepts.
2.0Comparison
2.1Program Structure
VB.NET
C#.NET
Imports System
Namespace Hello
Class HelloWorld
Overloads Shared Sub Main(ByVal args() As String)
Dim name As String = "VB.NET"
'See if an argument was passed from the command line
If args.Length = 1 Then name = args(0)
Console.WriteLine("Hello, " & name & "!")
End Sub
End Class
End Namespace
using System;
namespace Hello {
public class HelloWorld {
public static void Main(string[] args) {
string name = "C#";
// See if an argument was passed from the command line
if (args.Length == 1)
name = args[0];
Console.WriteLine("Hello, " + name + "!");
}
}
}
2.2Comments
VB.NET
C#.NET
' Single line only REM Single line only
''' <summary>XML comments</summary>
// Single line
/* Multiple
line */
/// <summary>XML comments on single line</summary>
/** <summary>XML comments on multiple lines</summary> */
2.3Data Types
VB.NET
C#.NET
Value Types
Boolean
Byte, SByte
Char
Short, UShort, Integer, UInteger, Long, ULong
Single, Double
Decimal
Date
Reference Types
Object
String
Initializing
Dim correct As Boolean = True
Dim b As Byte = &H2A 'hex
Dim o As Byte = &O52 'octal
Dim person As Object = Nothing
Dim name As String = "Dwight"
Dim grade As Char = "B"c
Dim today As Date = #12/31/2007 12:15:00 PM#
Dim amount As Decimal = 35.99@
Dim gpa As Single = 2.9!
Dim pi As Double = 3.14159265
Dim lTotal As Long = 123456L
Dim sTotal As Short = 123S
Dim usTotal As UShort = 123US
Dim uiTotal As UInteger = 123UI
Dim ulTotal As ULong = 123UL
Type Information Dim x As Integer
Console.WriteLine(x.GetType()) ' Prints System.Int32
Console.WriteLine(GetType(Integer)) ' Prints System.Int32
Console.WriteLine(TypeName(x)) ' Prints Integer
Type Conversion
Dim d As Single = 3.5
Dim i As Integer = CType(d, Integer) ' set to 4 (Banker's rounding)
i = CInt(d) ' same result as CType
i = Int(d) ' set to 3 (Int function truncates the decimal)
object person = null;
string name = "Dwight";
char grade = 'B';
DateTime today = DateTime.Parse("12/31/2007 12:15:00");
decimal amount = 35.99m;
float gpa = 2.9f;
double pi = 3.14159265;
long lTotal = 123456L;
short sTotal = 123;
ushort usTotal = 123;
uint uiTotal = 123;
ulong ulTotal = 123;
Type Information
int x;
Console.WriteLine(x.GetType()); // Prints System.Int32
Console.WriteLine(typeof(int)); // Prints System.Int32
Console.WriteLine(x.GetType().Name); // prints Int32
Type Conversion
float d = 3.5f;
int i = (int)d; // set to 3 (truncates decimal)
2.4Constants
VB.NET
C#.NET
Const MAX_STUDENTS As Integer = 25
' Can set to a const or var; may be initialized in a constructor ReadOnly MIN_DIAMETER As Single = 4.93
const int MAX_STUDENTS = 25;
// Can set to a const or var; may be initialized in a constructor readonly float MIN_DIAMETER = 4.93f;
2.5Enumerations
VB.NET
C#.NET
Enum Action
Start
[Stop] ' Stop is a reserved word
Rewind
Forward End Enum
Enum Status
Flunk = 50
Pass = 70
Excel = 90 End Enum
Dim a As Action = Action.Stop
If a <> Action.Start Then _
Console.WriteLine(a.ToString & " is " & a) ' Prints "Stop is 1"
Console.WriteLine(Status.Pass) ' Prints 70
Console.WriteLine(Status.Pass.ToString()) ' Prints Pass
Note: && and || perform short-circuit logical evaluations
String Concatenation
+
2.7Choices
VB.NET
C#.NET
greeting = IIf(age < 20, "What's up?", "Hello")
' One line doesn't require "End If" If age < 20 Then greeting = "What's up?" If age < 20 Then greeting = "What's up?" Else greeting = "Hello"
' Use : to put two commands on same line If x <> 100 And y < 5 Then x *= 5 : y *= 2
' Preferred If x <> 100 And y < 5 Then
x *= 5
y *= 2 End If
' To break up any long single line use _ If whenYouHaveAReally < longLine And _
itNeedsToBeBrokenInto2 > Lines Then _
UseTheUnderscore(charToBreakItUp)
'If x > 5 Then
x *= y ElseIf x = 5 Then
x += y ElseIf x < 10 Then
x -= y Else
x /= y End If
Select Case color ' Must be a primitive data type Case "pink", "red"
r += 1 Case "blue"
b += 1 Case "green"
g += 1 Case Else
other += 1 End Select
// Multiple statements must be enclosed in {} if (x != 100 && y < 5) {
x *= 5;
y *= 2;
}
No need for _ or : since ; is used to terminate each statement.
if (x > 5)
x *= y; else if (x == 5)
x += y; else if (x < 10)
x -= y; else
x /= y;
// Every case must end with break or goto case switch (color) { // Must be integer or string case "pink": case "red": r++; break; case "blue": b++; break; case "green": g++; break; default: other++; break; // break necessary on default
}
2.8Loops
VB.NET
C#.NET
Pre-test Loops:
While c < 10
c += 1 End While
Do Until c = 10
c += 1 Loop
Do While c < 10
c += 1 Loop
For c = 2 To 10 Step 2
Console.WriteLine(c) Next
Post-test Loops:
Do
c += 1 Loop While c < 10
Do
c += 1 Loop Until c = 10
' Array or collection looping
Dim names As String() = {"Fred", "Sue", "Barney"} For Each s As String In names
Console.WriteLine(s) Next
' Breaking out of loops
Dim i As Integer = 0
While (True)
If (i = 5) Then Exit While
i += 1
End While
' Continue to next iteration
For i = 0 To 4
If i < 4 Then Continue For
Console.WriteLine(i) ' Only prints 4
Next
Pre-test Loops:
// no "until" keyword while (c < 10)
c++;
for (c = 2; c <= 10; c += 2)
Console.WriteLine(c);
Post-test Loop:
do
c++; while (c < 10);
// Array or collection looping
string[] names = {"Fred", "Sue", "Barney"}; foreach (string s in names)
Console.WriteLine(s);
// Breaking out of loops
int i = 0;
while (true) {
if (i == 5) break;
i++;
}
// Continue to next iteration
for (i = 0; i < 5; i++) {
if (i < 4) continue;
Console.WriteLine(i); // Only prints 4
}
2.9Arrays
VB.NET
C#.NET
Dim nums() As Integer = {1, 2, 3}
For i As Integer = 0 To nums.Length - 1
Console.WriteLine(nums(i))
Next
' 4 is the index of the last element, so it holds 5 elements
Dim names(4) As String
names(0) = "David"
names(5) = "Bobby" ' Throws System.IndexOutOfRangeException
' Resize the array, keeping the existing values (Preserve is optional) ReDim Preserve names(6)
Dim twoD(rows-1, cols-1) As Single
twoD(2, 0) = 4.5
Dim jagged()() As Integer = { _
New Integer(4) {}, New Integer(1) {}, New Integer(2) {} }
jagged(0)(4) = 5
int[] nums = {1, 2, 3};
for (int i = 0; i < nums.Length; i++)
Console.WriteLine(nums[i]);
// 5 is the size of the array
string[] names = new string[5];
names[0] = "David";
names[5] = "Bobby"; // Throws System.IndexOutOfRangeException
// C# can't dynamically resize an array. Just copy into new array.
string[] names2 = new string[7];
Array.Copy(names, names2, names.Length); // or names.CopyTo(names2, 0);
float[,] twoD = new float[rows, cols];
twoD[2,0] = 4.5f;
int[][] jagged = new int[3][] {
new int[5], new int[2], new int[3] };
jagged[0][4] = 5;
2.10 Functions
VB.NET
C#.NET
' Pass by value (in, default), reference (in/out), and reference (out) Sub TestFunc(ByVal x As Integer, ByRef y As Integer, ByRef z As Integer)
x += 1
y += 1
z = 5 End Sub
Dim a = 1, b = 1, c As Integer ' c set to zero by default
TestFunc(a, b, c)
Console.WriteLine("{0} {1} {2}", a, b, c) ' 1 2 5
' Accept variable number of arguments Function Sum(ByVal ParamArray nums As Integer()) As Integer
Sum = 0
For Each i As Integer In nums
Sum += i
Next End Function ' Or use Return statement like C#
Dim total As Integer = Sum(4, 3, 2, 1) ' returns 10
' Optional parameters must be listed last and must have a default value Sub SayHello(ByVal name As String, Optional ByVal prefix As String = "")
Console.WriteLine("Greetings, " & prefix & " " & name) End Sub
// Pass by value (in, default), reference (in/out), and reference (out)
void TestFunc(int x, ref int y, out int z) {
x++;
y++;
z = 5;
}
int a = 1, b = 1, c; // c doesn't need initializing
TestFunc(a, ref b, out c);
Console.WriteLine("{0} {1} {2}", a, b, c); // 1 2 5
// Accept variable number of arguments
int Sum(params int[] nums) {
int sum = 0;
foreach (int i in nums)
sum += i;
return sum;
}
int total = Sum(4, 3, 2, 1); // returns 10
/* C# doesn't support optional arguments/parameters. Just create two different versions of the same function. */
void SayHello(string name, string prefix) {
Console.WriteLine("Greetings, " + prefix + " " + name);
}
Special character constants
vbCrLf, vbCr, vbLf, vbNewLine
vbNullString
vbTab
vbBack
vbFormFeed
vbVerticalTab
""
' String concatenation (use & or +)
Dim school As String = "Harding" & vbTab
school = school & "University" ' school is "Harding (tab) University"
' Chars
Dim letter As Char = school.Chars(0) ' letter is H
letter = Convert.ToChar(65) ' letter is A
letter = Chr(65) ' same thing Dim word() As Char = school.ToCharArray() ' word holds Harding
' No string literal operator
Dim msg As String = "File is c:"temp"x.dat"
' String comparison
Dim mascot As String = "Bisons"
If (mascot = "Bisons") Then ' true
If (mascot.Equals("Bisons")) Then ' true
If (mascot.ToUpper().Equals
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