A Comparison Of .net COBOL, Visual Basic and C#

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)
         End If
         Console.WriteLine("Hello, " & name & "!")
      End Sub
   End Class
   End Namespace
End Class

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 + "!");
      }
   }
} 

      $set sourceformat(free)
      $set ilusing"System"
      *> Note, no direct syntax for specifying a default namespace;
class-id. HelloWorld as "Hello.Helloworld".
static.
  method-id. Main.
  local-storage section.
  01 nam string.
  procedure division using by value args as string occurs any.
      *> See if an argument was passed from the command line
      if args::"Length" = 1
          set nam to args(1)
      end-if
      display "Hello, ", nam, "!"
      *> or, if preferred...
      invoke type "Console"::"WriteLine"(string::"Concat"("Hello, ", nam, "!"))
   end method Main.
end static.
end class HelloWorld.

' 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> */</span>

      * Single line only, "old-style" COBOL comment with '*' in column 7
               *> inline comment may follow Cobol statements etc.
         *>> <summary>XML comments</summary>

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)

Value Types
bool
byte, sbyte
char
short, ushort, int, uint, long, ulong
float, double
decimal
DateTime   (not a built-in C# type)

Reference Types
object
string

Initializing
bool correct = true;
byte b = 0x2A;   // hex

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)

Value Types
condition-value
binary-char (unsigned)
character
binary-short, binary-long, binary-double (unsigned)
float-short, float-long
decimal
DateTime (not a built-in COBOL type

Reference types
object
string

Initializing
01 correct condition-value value true.
01 b binary-char unsigned value h"2a".  *> Hex
01 o binary-char ussigned value o"52".  *> Octal
01 person object value null.
01 nam string value "Dwight".
01 grade character value "B".
01 today type "DateTime" value type "DateTime"::"Parse"("12/31/2007 12:15:00").
01 amount decimal value 35.99.
01 gpa float-short value 2.9.
01 pi float-long value 3.14159265.
01 lTotal binary-double value 123456.
01 sTotal binary-short value 123.
01 usTotal binary-short unsigned value 123.
01 uiTotal binary-long value 123.
01 ulTotal binary-long unsigned value 123.

Type Information
01 x binary-long.
display x::"GetType"          *> Prints System.Int32
display type of binary-long   *> Prints System.Int32
display x::"GetType"::"Name"  *> Prints Int32

Type Conversion
01 d float-short value 3.5.   *> automatic conversion
set i to d as binary-long     *> set to 3 (truncates decimal)

COBOL types not supported in C# or VB.Net
*> Only a few examples here
01 displayNumber pic 9(9).99.
01 computeNumber pic 9(9)V99.
01 alphaNumberic pic a(23).
01 binaryStorage pic x(12).
*> Also groups and redefines - a few examples
01 arecord.
   03 aSubRecord pic x(10).
   03 aUnion     pic 9(10) redefines aSubrecord.

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; 

78 MAX_STUDENTS value 25.  *> optionally public, binary-long...

*> Currently no direct COBOL equivalent of 'readonly'

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

enum Action {Start, Stop, Rewind, Forward};
enum Status {Flunk = 50, Pass = 70, Excel = 90};

Action a = Action.Stop;
if (a != Action.Start)
  Console.WriteLine(a + " is " + (int) a);   // Prints "Stop is 1"

Console.WriteLine((int) Status.Pass);        // Prints 70
Console.WriteLine(Status.Pass);              // Prints Pass

   *> enum Action...      
   enum-id. Action.
      78 #Start.   *> Start is a reserved word
      78 #Stop.
      78 #Rewind.
      78 #Forward.
   end enum Action.
   *>enum Status...
   enum-id. Stat as "Status".
      78 Flunk value 50.
      78 Pass value 70.
      78 Excel value 90.
   end enum Action.
   display type "Status"::"Pass" as binary-long *> prints 70
   display type "Status"::"Pass" *> prints Pass

   
 

Comparison
=  <  >  <=  >=  <>

Arithmetic
+  -  *  /
Mod
\  (integer division)
^  (raise to a power)

Assignment
=  +=  -=  *=  /=  \=  ^=  <<=  >>=  &=

Bitwise
And   Or   Xor   Not   <<   >>

Logical
AndAlso   OrElse   And   Or   Xor   Not

'Note: AndAlso and OrElse perform short-circuit logical evaluations

String Concatenation
& 

Comparison
==  <  >  <=  >=  !=

Arithmetic
+  -  *  /
%  (mod)
/  (integer division if both operands are ints)
Math.Pow(x, y)

Assignment
=  +=  -=  *=  /=   %=  &=  |=  ^=  <<=  >>=  ++  --

Bitwise
&   |   ^   ~   <<   >>

Logical
&&   ||   &   |   ^   !

//Note: && and || perform short-circuit logical evaluations

String Concatenation
+

Comparison
= < > <= >= <>

Arithmetic
+ - * /
function mod
*>no direct COBOL equivalent to integer division
**

Assignment
move, set, compute

Bitwise
b-and, b-or, b-xor, b-not, b-left, b-right

Logical
and, or, not

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

greeting = age < 20 ? "What's up?" : "Hello";

// Good practice is that all consequents are enclosed in {}
// or are on the same line as if.
if (age < 20) greeting = "What's up?";
else
{
   greeting = "Hello";
}

// 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
}

*>greeting = age < 20 ? has no directly equivalent syntax in COBOL

if age < 20
   move "What's up?" to greeting
else
   move "Hello" to greeting
end-if



if x not = 100 and y < 5
   multiply 5 by x
   multiply 2 by y
end-if



*>No need for _ or : since statement is terminated by end-if
*> evalute is prefered in COBOL rather than if/else if/else
evaluate x
   when > 5
      multiply y by x
   when 5
      add y to x
   when < 10
      subtract y from x
   when other
      divide y into x
end-evaluate







evaluate color   *> can be any type
   when "pink"
   when "red"
      add 1 to r
   when "blue"
      add 1 to b
   when "green"
      add 1 to g
   when other
      add 1 to other-color
end-evaluate
               

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
   End If
   i += 1
End While 



Continue to next iteration
For i = 0 To 4
   If i < 4 Then
      Continue For
   End If
   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
}

Pre-test loops:
*> No WHILE keyword
perform until c >= 10
   add 1 to c
end-perform

perform varying c from 2 by 2 until c > 10
   display c
end-perform







Post-test loops:
perform with test after until c >= 10
   add 1 to c
end-perform



Array or collection looping
01 names string occurs any.
01 s string.
set content of names to ("Fred" "Sue" "Barney")
perform varying s through names
   display s
end-perform

Breaking out of loops:
01 i binary-long value 0.
perform until exit
   if i = 5
      exit perform
   end-if
   add 1 to i
end-perform



Continue to next iteration:
01 i binary-long value 0
perform varying i from 0 by 1 until i >= 5
   if i < 4
      exit perform cycle
   end-if
   display i *>Only prints 4
end-perform

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)
' Note however, that this produces a new copy of the array - it is not an in-place resize!

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;

01 nums binary-long occurs any values 1, 2, 3.
*> Can also do:
set content of nums to (1 2 3)

*> 5 is the size of the array
01 names string occurs 5.
*> Can also do:
01 names string occurs any.
set size of names to 5
set names(1) to "David"  *> first element indexed as 1
set names(6) to "Bobby"  *> throws System.IndexOutOfRangeException

*> COBOL cannot resize an array - use copy
01 names2 string occurs 7.
invoke type "Array"::"Copy"(names, names2, names::"Length")
*> or else:
invoke names::"CopyTo"(names2, 0)

01 twoD float-short occurs any, any.
set size of twoD to rows, cols

01 jagged binary-long occurs any, occurs any.
set size of jagged to 3
set size of jagged(1) to 5
set jagged(1 5) to 5

' 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

SayHello("Strangelove", "Dr.")
SayHello("Madonna")

// 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);
} 

void SayHello(string name) 
{ 
   SayHello(name, ""); 
}

method-id. TestFunc.
   procedure division using by value x as binary-long, 
                            by reference y as binary-long, 
                            output z as binary-long.
      add 1 to x, y
      move 5 to z
end method TestFunc.

01 a binary-long value 1.
01 b binary-long value 1.
01 c binary-long.  *> c doesn't need initializing

invoke self::"TestFunc"(value a reference b output c)
*> Or 
invoke self::"TestFunc"(a b c)
display a space b space c

*> sum is an intrinsic function in COBOL
01 total binary-long.
set total to function sum(4 3 2 1) *> returns 10

*> To create a non intrinsic variable argument list function:
Method-id. MySum.
01 i binary-long.
Procedure division using params nums as binary-long occurs any
                      returning mysum as binary-long.
    Perform varying i through nums
        Add i to mysum
    End-perform
    Goback
End method MySum.

*> then to call it:
method-id. main.
01 i binary-long.
    set i to self::"MySum"(1 2 3 4)
    display i
end method main.

*> COBOL doesn't support optional arguments/parameters.
*> Just create two different versions of the same function.  
method-id. SayHello.
   procedure division using by value nam as string, prefix as string.
      display "Greetings, " prefix space nam
   end method SayHello.

method-id. SayHello.
   procedure division using by value nam as string.
      invoke self::"SayHello"(nam "")
end method SayHello.

Special character constants (all also accessible from ControlChars class)
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("BISONS")) Then  ' true
If (mascot.CompareTo("Bisons") = 0) Then     ' true

' String matching with Like - Regex is more powerful
If ("John 3:16" Like "Jo[Hh]? #:*") Then   'true

' Substring
s = mascot.Substring(2, 3)) ' s is "son"

' Replacement
s = mascot.Replace("sons", "nomial")) ' s is "Binomial"

' Split
Dim names As String = "Frank,Becky,Ethan,Braden"
Dim parts() As String = names.Split(",".ToCharArray())   ' One name in each slot


' Date to string
Dim dt As New DateTime(1973, 10, 12)
Dim s As String = "My birthday: " & dt.ToString("MMM dd, yyyy")   ' Oct 12, 1973

' Integer to String
Dim x As Integer = 2
Dim y As String = x.ToString()     ' y is "2"

' String to Integer
Dim x As Integer = Convert.ToInt32("-5")     ' x is -5




' Mutable string
Dim buffer As New System.Text.StringBuilder("two ")
buffer.Append("three ")
buffer.Insert(0, "one ")
buffer.Replace("two", "TWO")
Console.WriteLine(buffer)         ' Prints "one TWO three" 

Escape sequences
\r    // carriage-return
\n    // line-feed
\t    // tab
\\    // backslash
\"    // quote



// String concatenation
string school = "Harding\t";
school = school + "University";   // school is "Harding (tab) University"

// Chars
char letter = school[0];              // letter is H
letter = Convert.ToChar(65);          // letter is A
letter = (char)65;                    // same thing
char[] word = school.ToCharArray();   // word holds Harding



// String literal
string msg = @"File is c:\temp\x.dat";
// same as
string msg = "File is c:\\temp\\x.dat";

// String comparison
string mascot = "Bisons";
if (mascot == "Bisons")                 // true
if (mascot.Equals("Bisons"))            // true
if (mascot.ToUpper().Equals("BISONS"))  // true
if (mascot.CompareTo("Bisons") == 0)    // true

// String matching - No Like equivalent, use Regex


// Substring
s = mascot.Substring(2, 3))     // s is "son"

// Replacement
s = mascot.Replace("sons", "nomial"))     // s is "Binomial"

// Split
string names = "Frank,Becky,Ethan,Braden";
string[] parts = names.Split(",".ToCharArray());   // One name in each slot


// Date to string
DateTime dt = new DateTime(1973, 10, 12);
string s = dt.ToString("MMM dd, yyyy");     // Oct 12, 1973

// int to string
int x = 2;
string y = x.ToString();     // y is "2"

// string to int
int x = Convert.ToInt32("-5");     // x is -5




// Mutable string
System.Text.StringBuilder buffer = new System.Text.StringBuilder("two ");
buffer.Append("three ");
buffer.Insert(0, "one ");
buffer.Replace("two", "TWO");
Console.WriteLine(buffer);     // Prints "one TWO three"

Escape sequences
x"0a"  *> line-feed
x"09"  *> tab
"\"    *> backslash
""     *> quote




*> string concatenation
01 school string value "Harding" & x"09".
    set school to string::"Concat"(school, "University")  *> school is "Harding (tab) University"

*> Chars
01 letter character.
01 word character occurs any.
    set letter to school::"Chars"(0)   *> letter is H
    set letter to type "Convert"::"ToChar"(65) *> letter is A
    set letter to 65 as character      *> same thing
    set word to school::"ToCharArray"  *>word holds Harding

*> String literal
01 msg string value "File is c:\temp\x.dat".



*>String comparison
01 mascot string value "Bisons".
    if mascot = "Bisons"    *> true
    if mascot::"Equals"("Bisons")  *> true
    if mascot::"ToUpper"::"Equals"("BISONS")  *> true
    if mascot::"CompareTo"("Bisons") = 0  *> true

*> String matching - no Like equivalent , use Regex


*> Substring
    set s to mascot::"Substring"(2 3) *> s is "son"

*> Replacement
    set s to mascot::"Replace"("sons" "nomial")  *> s is "Binomial"

*> Split
01 names string value "Frank,Becky,Ethan,Braden".
01 parts string occurs any.
    set parts to names::"Split"(",")

*> Date to string
01 dt type "DateTime" value new "DateTime"(1973, 10, 12).
01 s string.
    set s to dt::"ToString"("MMM dd, yyyy")  *> Oct 12, 1973

*> int to string
01 x string.
01 y binary-long value 2.
    set x to type x::"ToString"   *> x is "2"
        
*> string to int
01 x binary-long.
    set x to type "Convert"::"ToInt32"("-5")   *> x is -5
    
*> Mutable string
01 buffer type "System.Text.StringBuilder" value new "System.Text.StringBuilder"("two ").
    invoke buffer::"Append"("three ")
    invoke buffer::"Insert"(0, "one ")
    invoke buffer::"Replace("two" "TWO"
    display buffer   *> Prints "one TWO three"
    

' Throw an exception
Dim ex As New Exception("Something is really wrong.")
Throw  ex 

' Catch an exception
Try 
  y = 0
  x = 10 / y
Catch ex As Exception When y = 0 ' Argument and When is optional
  Console.WriteLine(ex.Message)
Finally
  Beep()
End Try

' Deprecated unstructured error handling
On Error GoTo MyErrorHandler
...
MyErrorHandler: Console.WriteLine(Err.Description)

// Throw an exception
Exception up = new Exception("Something is really wrong.");
throw up;  // ha ha

// Catch an exception
try 
{ 
  y = 0;
  x = 10 / y;
}
catch (Exception ex) // Argument is optional, no "When" keyword 
{
  Console.WriteLine(ex.Message);
}
finally 
{
  Microsoft.VisualBasic.Interaction.Beep();
} 

*> Throw an exception
01 up type "Exception" value new "Exception"("Something is really wrong.");
raise up  *> ha ha

*> Catch an exception
try
  set y to 0;
  compute x = 10 / y
catch (type "Exception" ex)   *> Argument is optional, no "When" keyword 
  display ex.Message
finally
  invoke type "Microsoft.VisualBasic.Interaction"::"Beep"
end-try

Namespace Harding.Compsci.Graphics 
  ...
End Namespace

' or

Namespace Harding
  Namespace Compsci
    Namespace Graphics 
      ...
    End Namespace
  End Namespace
End Namespace

Imports Harding.Compsci.Graphics 

namespace Harding.Compsci.Graphics 
{
  ...
}

// or

namespace Harding 
{
  namespace Compsci 
  {
    namespace Graphics 
    {
      ...
    }
  }
}

using Harding.Compsci.Graphics;

*> At the file level
$set ilnamespace "Harding.Compsci.Graphics"

*> The directive can also be set as a project
*> level to apply the name space to all classes in the project.

' Accessibility keywords 
Public
Private
Friend                    
Protected
Protected Friend
Shared

' Inheritance
Class FootballGame
  Inherits Competition
  ...
End Class 

' Interface definition
Interface IAlarmClock 
  ...
End Interface

' Extending an interface 
Interface IAlarmClock 
  Inherits IClock
  ...
End Interface

' Interface implementation
Class WristWatch 
  Implements IAlarmClock, ITimer 
   ...
End Class

//Accessibility keywords 
public
private
internal
protected
protected internal
static

// Inheritance
class FootballGame : Competition 
{
  ...
}


// Interface definition
interface IAlarmClock 
{
  ...
}

// Extending an interface 
interface IAlarmClock : IClock 
{
  ...
}


// Interface implementation
class WristWatch : IAlarmClock, ITimer 
{
   ...
}

*> Accessibility keywords
public
private
internal
protected
protected internal
static

*> Inheritance
class-id. FootballGame inherits type "Competition".
  ...
end class FootballGame.


*> Interface definition
interface-id. IAlarmClock.
  ...
end interface IAlarmClock.

*> Extending an interface 
interface-id IAlarmClock extends type "IClock".
  ...
end interface IAlarmClock.


*> Interface implementation
class-id. WristWatch implements type "IAlarmClock", type "ITimer".
   ...
end class WristWatch.

Class SuperHero
  Private _powerLevel As Integer 

  Public Sub New() 
    _powerLevel = 0 
  End Sub 

  Public Sub New(ByVal powerLevel As Integer) 
    Me._powerLevel = powerLevel 
  End Sub

  Protected Overrides Sub Finalize() 
   ' Desctructor code to free unmanaged resources 
    MyBase.Finalize() 
  End Sub
End Class

class SuperHero 
{
  private int _powerLevel;

  public SuperHero() 
  {
     _powerLevel = 0;
  }

  public SuperHero(int powerLevel) 
  {
    this._powerLevel= powerLevel; 
  }

  ~SuperHero() 
  {
    // Destructor code to free unmanaged resources.
    // Implicitly creates a Finalize method
  }
}

class-id. SuperHero.
01 _powerLevel binary-long.

method-id. new.
procedure division.
    set _powerLevel to 0
end method new.

method-id. new.
procedure division using by value powerLevel as binary-long.
    set _powerLevel to powerLevel
end method new.

method-id. Finalize override protected.
    *> Destructor code to free unmanaged resources.
end method Finalize.
end class SuperHero.

Dim hero As SuperHero = New SuperHero
' or
Dim hero As New SuperHero

With hero 
  .Name = "SpamMan" 
  .PowerLevel = 3 
End With 
hero.Defend("Laura Jones") 
hero.Rest()     ' Calling Shared method
' or
SuperHero.Rest()

Dim hero2 As SuperHero = hero  ' Both reference the same object 
hero2.Name = "WormWoman" 
Console.WriteLine(hero.Name)   ' Prints WormWoman

hero = Nothing    ' Free the object

If hero Is Nothing Then _ 
  hero = New SuperHero

Dim obj As Object = New SuperHero 
If TypeOf obj Is SuperHero Then _
  Console.WriteLine("Is a SuperHero object.")

  
  
  
  
  
' Mark object for quick disposal
Using reader As StreamReader = File.OpenText("test.txt")
  Dim line As String = reader.ReadLine()
  While Not line Is Nothing
    Console.WriteLine(line)
    line = reader.ReadLine()
  End While
End Using

SuperHero hero = new SuperHero(); 



// No "With" construct
hero.Name = "SpamMan"; 
hero.PowerLevel = 3; 


hero.Defend("Laura Jones");
SuperHero.Rest();   // Calling static method



SuperHero hero2 = hero;   // Both reference the same object 
hero2.Name = "WormWoman"; 
Console.WriteLine(hero.Name);   // Prints WormWoman

hero = null ;   // Free the object

if (hero == null)
  hero = new SuperHero();

Object obj = new SuperHero(); 
if (obj is SuperHero)
{ 
  Console.WriteLine("Is a SuperHero object.");
} 
  
  
  
// Mark object for quick disposal
using (StreamReader reader = File.OpenText("test.txt")) 
{
  string line;
  while ((line = reader.ReadLine()) != null)
  {
    Console.WriteLine(line);
  }
}

01 hero type "SuperHero" value new "SuperHero".
01 hero2 type "SuperHero".
01 obj object.
01 reader type "StreamReader".
01 lin string.

// No "With" construct
set hero::"Name" to "SpamMan"
set hero::"PowerLevel" to 3


invoke hero::"Defend"("Laura Jones")
invoke type "SuperHero"::"Rest"   *> Calling static method



set hero2 to hero      *> Both reference the same objectv
set hero2::"Name" to "WormWoman"
display hero::"Name"   *> Prints WormWoman

set hero to null       *> Free the object

if hero = null
    set hero to new "SuperHero"
end-if

set obj to new "SuperHero"
if obj is instance of type "SuperHero"
    display "Is a SuperHero object."
end-if

*> No 'using' construct in COBOL
try
    set reader to type "File"::"OpenText"("test.txt")
    perform until exit
        set lin to reader::"ReadLine"
        if lin = null
            exit perform
        end-if
    end-perform
finally
    if reader not = null
        invoke reader::"Dispose"
    end-if
end-try

Structure StudentRecord 
  Public name As String 
  Public gpa As Single 

  Public Sub New(ByVal name As String, ByVal gpa As Single) 
    Me.name = name 
    Me.gpa = gpa 
  End Sub 
End Structure

Dim stu As StudentRecord = New StudentRecord("Bob", 3.5) 
Dim stu2 As StudentRecord = stu   

stu2.name = "Sue" 
Console.WriteLine(stu.name)    ' Prints Bob
Console.WriteLine(stu2.name)   ' Prints Sue

struct StudentRecord 
{
  public string name;
  public float gpa;

  public StudentRecord(string name, float gpa) 
  {
    this.name = name;
    this.gpa = gpa;
  }
}
StudentRecord stu = new StudentRecord("Bob", 3.5f);
StudentRecord stu2 = stu;  

stu2.name = "Sue";
Console.WriteLine(stu.name);    // Prints Bob
Console.WriteLine(stu2.name);   // Prints Sue

      $set sourceformat(free) preservecase
valuetype-id. StudentRecord.
object.
01 #name string public.
01 gpa float-short public.
method-id. new.
procedure division using by value nam as string, gpa as float-short.
    set #name to nam
    set self::"gpa" to gpa
end method new.
end object.
end valuetype StudentRecord.

class-id. a.
static.
method-id. main.
01 stu type "StudentRecord" value new "StudentRecord"("Bob", 3.5).
01 stu2 type "StudentRecord".
procedure division.
    set stu2 to stu
    set stu2::"name" to "Sue"
    display stu::"name"   *> Prints Bob
    display stu2::"name"  *> Prints Sue
end method main.
end static.
end class a.

Private _size As Integer

Public Property Size() As Integer
  Get 
    Return _size 
  End Get 
  Set (ByVal Value As Integer) 
    If Value < 0 Then 
      _size = 0 
    Else 
      _size = Value 
    End If 
  End Set 
End Property

foo.Size += 1

private int _size;

public int Size 
{ 
  get 
  { 
    return _size; 
  } 
  set 
  { 
    if (value < 0)
    {    
      _size = 0; 
    }
    else
    {    
      _size = value; 
    }
  } 
}
foo.Size++;

      $set sourceformat(free) preservecase
class-id. MyClass.
object.
01 _size binary-long private.
method-id. get property #Size.
procedure division returning ret as binary-long.
    set ret to _size
end method.
method-id. set property #Size.
procedure division using by value val as binary-long.
    if val < 0
        set _size to 0
    else
        set _size to val
    end-if
end method.
end object.
end class MyClass.

class-id. a.
static.
method-id. main.
01 foo type "MyClass" value new"MyClass".
    add 1 to foo::"Size"
    display foo::"Size"
end method main.
end static.
end class a.

Delegate Sub MsgArrivedEventHandler(ByVal message As String)

Event MsgArrivedEvent As MsgArrivedEventHandler







' or to define an event which declares a delegate implicitly
Event MsgArrivedEvent(ByVal message As String)

AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback 
' Won't throw an exception if obj is Nothing
RaiseEvent MsgArrivedEvent("Test message") 
RemoveHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback
Imports System.Windows.Forms

Dim WithEvents MyButton As Button   ' WithEvents can't be used on local variable
MyButton = New Button

Private Sub MyButton_Click(ByVal sender As System.Object, _
  ByVal e As System.EventArgs) Handles MyButton.Click 
  MessageBox.Show(Me, "Button was clicked", "Info", _
    MessageBoxButtons.OK, MessageBoxIcon.Information) 
End Sub

delegate void MsgArrivedEventHandler(string message);

event MsgArrivedEventHandler MsgArrivedEvent;







// Delegates must be used with events in C#


MsgArrivedEvent += new MsgArrivedEventHandler(My_MsgArrivedEventCallback);
MsgArrivedEvent("Test message");    // Throws exception if obj is null
MsgArrivedEvent -= new MsgArrivedEventHandler(My_MsgArrivedEventCallback);



using System.Windows.Forms;

Button MyButton = new Button(); 
MyButton.Click += new System.EventHandler(MyButton_Click);

private void MyButton_Click(object sender, System.EventArgs e) 
{ 
  MessageBox.Show(this, "Button was clicked", "Info", 
    MessageBoxButtons.OK, MessageBoxIcon.Information); 
}

      $set sourceformat(free) preservecase
      $set ilusing"System"
delegate-id. MsgArrivedEventHandler.
procedure division using by value messag as string.
end delegate MsgArrivedEventHandler.

class-id. a.
static.
01 MsgArrivedEvent type "MsgArrivedEventHandler" event.

*> Delegates must be used with events in COBOL
  method-id. main.
      set MsgArrivedEvent to type "Delegate"::"Combine"
      (
        MsgArrivedEvent,
        new "MsgArrivedEventHandler"(self::"My_MsgArrivedEventCallback")
      ) as type "MsgArrivedEventHandler"
      
      invoke MsgArrivedEvent::"Invoke"("Test message")    *> Throws exception if obj is null
      
      set MsgArrivedEvent to type "Delegate"::"Remove"
      ( 
        MsgArrivedEvent,
        new "MsgArrivedEventHandler"(self::"My_MsgArrivedEventCallback")
      ) as type "MsgArrivedEventHandler"
      
      invoke self::"add_MsgArrivedEvent"
       (new "MsgArrivedEventHandler"(self::"My_MsgArrivedEventCallback"))
      invoke MsgArrivedEvent::"Invoke"("Test message 2")
  end method main.
  method-id. My_MsgArrivedEventCallback.
  procedure division using by value str as string.
      display str
  end method My_MsgArrivedEventCallback.
end static.
end class a.