The if Statement
An if statement consists of a boolean expression followed by one or more statements.
Syntax
The syntax of if statement is −
if expression then -- Statements will execute if the expression is true end if
If the boolean expression evaluates to true then the block of code inside the if statement is executed. If it evaluates to false, then the first set of code after the end of the if statement is executed.
Example
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) < 40 then
printf(1, "%s\n", {"This is true if statement!"})
end if
if (a + b) > 40 then
printf(1, "%s\n", {"This is not true if statement!"})
end if
This produces the following result −
This is true if statement!
The if…else Statement
An if statement can be followed by an optional else statement, which executes when the boolean expression is false.
Syntax
The syntax of if…else statement is as follows −
if expression then -- Statements will execute if the expression is true else -- Statements will execute if the expression is false end if
Example
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) < 40 then
printf(1, "%s\n", {"This is inside if statement!"})
else
printf(1, "%s\n", {"This is inside else statement!"})
end if
This produces the following result −
This is inside if statement!
The if…elsif…else Statement
An if statement can be followed by any number of optional elsif…else statement, which is very useful to test various conditions using single if…elsif statement.
Syntax
The syntax of if…elsif…else statement is as follows −
if expression1 then -- Executes when the Boolean expression 1 is true elsif expression2 then -- Executes when the Boolean expression 2 is true elsif expression3 then -- Executes when the Boolean expression 3 is true else -- Executes when none of the above condition is true. end if
Example
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) = 40 then
printf(1, "Value of (a + b ) is %d\n", a + b )
elsif (a + b) = 45 then
printf(1, "Value of (a + b ) is %d\n", a + b )
elsif (a + b) = 30 then
printf(1, "Value of (a + b ) is %d\n", a + b )
else
printf(1, "Value of (a + b ) is %d\n", 0 )
end if
This produces the following result −
Value of (a + b ) is 30
The if…label…then Statement
An if statement can have a label clause just before the first then keyword. Note that an elsif clause can not have a label.
An if…lable is used just to name the if block and label names must be double quoted constant strings having single or multiple words. The label keyword is a case sensitive and should be written as label.
Syntax
The syntax of label clause is as follows −
if expression label "Label Name" then -- Executes when the boolean expression is true end if
Example
#!/home/euphoria-4.0b2/bin/eui integer a = 10 integer b = 20 if (a + b) = 40 label "First IF Block" then printf(1, "Value of (a + b ) is %d\n", a + b ) elsif (a + b) = 45 then printf(1, "Value of (a + b ) is %d\n", a + b ) elsif (a + b) = 30 then printf(1, "Value of (a + b ) is %d\n", a + b ) else printf(1, "Value of (a + b ) is %d\n", 0 ) end if
This produces the following result −
Value of (a + b ) is 30
Nested if…else Statement
It is always legal to nest if…else statements. This means you can have one if-else statement within another if-else statements.
Syntax
The syntax of nested if…else is as follows −
if expression1 then
-- Executes when the boolean expression1 is true
if expression2 then
-- Executes when the boolean expression2 is true
end if
end if
Example
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
integer c = 0
if c = 0 then
printf(1, "Value of c is equal to %d\n", 0 )
if (a + b) = 30 then
printf(1, "Value of (a + b ) is equal to %d\n", 30)
else
printf(1, "Value of (a + b ) is equal to %d\n", a + b )
end if
else
printf(1, "Value of c is equal to %d\n", c )
end if
This produces the following result −
Value of c is equal to 0 Value of (a + b ) is equal to 30
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