Functions and parameters

[paulm]

Hi

Can I update function parameters in a function ... I have some code but it does need seem to pass back variables updated in functions ... in the example below c1 and c2 are not updated following the call to updatemyvariables??????

Thanks - any help appreciated

Paul

var c1; //global variable
var c2; //global variable

function preMain() {
c1 = 0;
c2 = 0;
}

function main() {

updatemyvariable(c1,c2);


}

function updatemyvariable(x1,x2) {

x1 = x1+1;
x2 = x2+1;
}

[ACM]

Paul
Assuming I understood what you are trying to do here is how you would need to write the script.
Alex

var c1; 
var c2; 
 
function preMain() {
    c1 = 0;
    c2 = 0;
}
 
function main() {
    updatemyvariable(c1,c2);
    debugPrintln(c1+"  "+c2);
}
 
function updatemyvariable(x1,x2) {
    c1 = x1+1;
    c2 = x2+1;
} 

[paulm]

Alex

no not really - I have a buch of global arrays and an update function that adds an element to any array etc ... I want to have one function be able to pass in 4 of the arrays at a time and update them in the function otherwise i have to repeat the update code for each array ...
I cannot know in the function which global variable is being passed in so i cannot reference it directly ????

Thanks

Paul

var c2;
var c1;

function main () {

updatemyvars(c1,c2,open(0),close(0));

}

function updatemyvars(x,y,a,b) {

x = x + a;
y = y + b;

}

[paulm]

Alex

In other words ... in the update function I don't know what is being passed in so I cannot reference it directly...

var c1;
var c2;
var c3;

function preMain() {

c1 = 0;
c2 = 0;
c3 = 0;

}

function main () {

if (getMinute() == 1) updatemyvariable (c1,c2);

// here i want c2 = c2 + open(0);

else if (getMinute() == 3) updatemyvariable (c2,c3);

// here i want c2 = c2 + close(0);

}

function updatemyvariable (x,y) {

x = x+ close(0);
y = y + open(0);

}

[ACM]

Paul
As I understand it when you pass to a function a variable that is a number this is passed in by value ie the actual number is passed to the function and not the variable that represents the number. In this case the passed value will be modified by the function but only locally while the external variable will not be updated by the function.
In order to update the external variable this needs to be an object so that you can pass it to the function by reference ie pass the actual variable and not its value. In this case the changes applied to the variable in the function will be global. Enclosed below is an example of how you could accomplish this.
You can read more on the subject of passing variables in JavaScript in this article I found on the net.
Alex

var c1 = new Object(); 
var c2 = new Object(); 
 
function preMain() {
    c1.myValue = 0;
    c2.myValue = 0;
}
 
function main() {
    updatemyvariable(c1,c2);
    debugPrintln(c1.myValue+"  "+c2.myValue);
}
 
function updatemyvariable(x1,x2) {
    x1.myValue = x1.myValue+1;
    x2.myValue = x2.myValue+1;
} 

[paulm]

Alex

Thanks again ... that makes perfect sense

Paul

[ACM]

Paul
You are most welcome
Alex