Conditional Statements

2008 October 01 | 10:06 pm

Conditional statements, also known as control statements, are used where your program must evaluate whether a logical statement is true or false. These include, but are not limited to:

Click each link to expand and collapse each sample window...

IF-THEN-ELSE

General form:
IF(CONDITION evaluates to TRUE) THEN
DO SOMETHING
ELSE
DO SOMETHING ELSE

• C/C++ / C#.NET / Java
  if(x==1)
{
// do something
}
else
{
// do something else
}
• VisualBasic.NET
  If foo = bar Then
' do something
Else
' do something else
End If

WHILE, DO-WHILE, and DO-UNTIL loops

General form:
WHILE(CONDITION evaluates to TRUE)
DO SOMETHING
LOOP

DO
SOMETHING
WHILE(CONDITION evaluates to TRUE)

DO
SOMETHING
UNTIL(CONDITION evaluates to TRUE)

• C/C++ / C#.NET / Java
  while(choice != 'x')
{
// do something
}

do
{
// do something
}while(choice != 'x')

do
{
// do something
}while(choice == 'x')
• VisualBasic.NET
  While repeat = True
' do something
End While

Do While repeat = True
' do something
Loop

Do Until repeat = False
' do something
Loop

FOR and FOREACH loops

General form:
FOR(ITERATOR; CONDITION; INCREMENTOR)
DO SOMETHING

FOREACH(ELEMENT in COLLECTION)
DO SOMETHING

• C/C++
  for(int i=0; i<0; i++)
{
// do something
}

for each(Control ctrl in this.MainForm.Controls)
{
// do something
}
• C#.NET
  int x = 10;

for( int i=0; i=< x; i++)
{
// do something
}

foreach (Control ctrl in this.Controls)
{
// do something
}
• Java
  int x = 10;

for( int i=0; i=< x; i++)
{
// do something
}

for (Control ctrl : this.Controls)
{
// do something
}
• VisualBasic.NET
  For Each ctrl As Control In Me.MainForm.Controls
' do something
Next ctrl

SWITCH or SELECT CASE statements

General form:
SWITCH (COMPARITOR)
CASE (VALUE1):
DO SOMETHING
BREAK
CASE (VALUE2):
DO SOMETHING
BREAK
CASE (DEFAULT VALUE):
DO SOMETHING
BREAK
END SWITCH

• C/C++ / C#.NET / Java
  switch(rdb.Name)
{
case button1:
// do something
break;
case button2:
// do something
break;
default:
// do something
break;
}
• VisualBasic.NET
  Select Case option
Case 0
' do something
Case 1
' do something
Case Else
' do something
End Select