Functions That Return Values - Crestron SIMPL+ Programming Manual

Crestron simpl+ software: software guide

Hide thumbs Also See for SIMPL+:

Reference manual (374 pages)

Table Of Contents

Table of Contents

Software



36 • SIMPL+

localStr = left(var3, 10);

}

Notice that the function shown above has three arguments, named var1, var2, and

var3. var1 and var2 are integers, while var3 is a string. Shown below is an example

of how to call this function from elsewhere in your program:

Call some_function( intVal1, 5+1, stringVal1);

Here we are assuming that the variable int1 has been defined as an integer earlier in

the program, as has the string variable, string1. Also note that the second argument is

a constant, and not a variable at all. This simply means that inside some_function,

the value of var2 will be set to 6.

ByRef, ByVal, and ReadOnlyByRef

When defining a function's argument list, there are optional keywords you can use

which give you greater control over the behavior of the arguments. These keywords

are ByRef, ByVal, and ReadOnlyByRef.

What do these keywords mean? Essentially they describe the way that SIMPL+

passes variables to the function. When a function argument is defined as ByRef, any

variable that is passed to this argument will pass enough information about itself to

allow the function to modify the value of the original variable. The term ByRef is

used because we say a "reference" to the original variable is passed to the function.

This reference can be thought of the memory location where the original variable

lives. When a function argument is defined as "ByVal", only the value of the

variable and not the variable itself is passed to the function, so the original variable

cannot be modified within the function. As an example, below is a function, which

takes two strings as arguments. It inserts one string into the other at a specified

character location:

FUNCTION insertString(ByRef STRING string1, ByVal STRING

string2, ByVal INTEGER position)

{

STRING leftpart[20], rightpart[20];

leftpart = left(string1,position);

rightpart = right(string1,position);

string1 = leftpart + string2 + rightpart;

}

In this example, note that only the first string argument, string1, was defined as

ByRef.