programming-for-dummies

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Passing Parameters
Defining a function in the C language looks like this:
datatype function_name (parameter list)
{
commands
return value
}
Inside the function, one or more commands must calculate a new result.
Then you use the RETURN keyword to define what value to store in the function
name. Whatever value this is, it must be the same data type that you
defined for the function name in the first line. So if you defined a function as
a String data type, you can’t return an integer value from that function.
A typical function in BASIC might look like this:
FUNCTION ConvertC2F (Temperature AS SINGLE) AS SINGLE
Temperature = ((9/5) * Temperature) + 32
RETURN Temperature
END FUNCTION
The function name ConvertC2F can hold a Single data type.
Unlike a subprogram that may or may not return a modified value, functions
always return a value. To call a function, you must assign the function name
to a variable or use the function name itself as a variable, such as
PRINT “Temperature in Fahrenheit = “; ConvertC2F (12)
Because functions always return a value, they (almost always) have a parameter
list. So you can identify functions in a program by looking for the parameter
list in parentheses.
DIM Temp AS SINGLE
Temp = 12
PRINT “Temperature in Celsius = “; Temp
PRINT “Temperature in Fahrenheit = “; ConvertC2F (Temp)
END
FUNCTION ConvertC2F (Temperature AS SINGLE) AS SINGLE
Temperature = ((9/5) * Temperature) + 32
RETURN Temperature
END FUNCTION
Unlike a subprogram that you can call just by typing its name on a line by
itself, you can call a function only by using that function name as if it’s a
variable.