MT4 Variables

[color=SeaGreen]// the [color=Red][b]&[/b][/color] marks those arguments that the function may change
// and changes will be visible to the [b]caller[/b]. normally the argument 
// list of a function is a one-way street and changes are only visible
// [b]inside[/b] the function.
//
// The default, passing [b]"by value"[/b], means only a copy of the value 
// of the variable is passed, not the variable[b] itself[/b].[/color][color=SeaGreen] The variable inside 
// the function is [b]not the same[/b] as outside, its a copy.
[/color] [color=SeaGreen]//
// Putting a [color=Red][b]&[/b][/color] in front of it means the variable [b]itself[/b] will be passed 
// and can be modified by the function. This is called [color=Red][b]"by reference"[/b][/color][/color]

Int NewValue(int new, int [color=Red][b]&[/b][/color]old){
   int supervalue;
 
   if (old > something){
      old=new;
   }
 
   if (condition){
      supervalue = iSomething(old);
      return (supervalue);
   }
}
 
[color=Blue] // declare the variable static. It will be local to the start() function
// but will remember it's value on subsequent calls.[/color] 
start(){
   [b][color=Blue]static[/color][/b] int old ; [color=SeaGreen]// will be initialized to zero only when used the [b]first[/b] time[/color]
   int new ;
   int SVal = 0;
   new = iMA(...);

   [color=SeaGreen]// value of old can only be changed by the function if
   // the argument is declared [color=Red][b]"by reference"[/b][/color] [/color]
   SVal = NewValue (new,old); reference
   Print (old + new + SVal);
}