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Function - a piece of code or algorithm that performs a specific sequence of operations. Each function may include:

• function name
• return value
• formal parameters
• function body

Example:

int multiplication(int a, int b)
{
  return a*b;
}

Function name - "multiplication" ; return value - int , formal parameters "a" and "b" (both int types), function body consists of a single operator - return a*b;

Parameters can be passed into the function both by value and by reference. When parameters are passed by value, they do not change after the execution of the function.

Example:

int Initialize()
{return(0);}
int Run()
{ 
  int a=1;
  changeA(a);
  System.Print("a="+a);
  return(0);
}
void changeA(int a)
{
  a=2;
}
int DeInitialize(){return(0);}

Output:

Parameters can be passed to function by reference. In that case, after the function is executed, parameters values may change. For this purpose the keyword &out must be specified between the parameter type and its name.

int Initialize()
{return(0);}
int Run()
{ 
  int a=1;
  changeA(a);
  System.Print("a="+a);
  return(0);
}
void changeA(int &out a)
{
  a=2;
}
int DeInitialize(){return(0);}

Output:

The parameters passed to the function can have default values. If any parameter is set by default, then all subsequent parameters should be set by default.

Example:

int Initialize()
{return(0);}
int Run()
{ 
  System.Print("sum1="+sum(2));
  System.Print("sum2="+sum(10,20,30));
  return(0);
}
int sum(int a, int b=3, int c=4)
{
  return a+b+c;
}
int DeInitialize(){return(0);}

Output:

sum1 = 9
sum2 = 60

The function can return a reference to a global variable. Using this reference, recording and reading the value of the global variable may be performed.

extern int a1=0;
extern int a2=0;
extern int a3=0;
extern int a4=0;
extern int a5=0;

int Initialize()
{return(0);}
int Run()
{ 
  for(int i=0;i<5;i++)
  {
    changeGlobal(i)=7;
  }
  for(int i=0;i<5;i++)
  {
   System.Print("i="+i+" value="+changeGlobal(i));
  }
  return(0);
}
int DeInitialize(){return(0);}
int& changeGlobal(int i)
{
  switch(i)
  {
  	case 1: return a1;
  	case 2: return a2;
  	case 3: return a3;
  	case 4: return a4;
  	case 5: return a5; 	
  }
  return a5;
}

Output:

i=0 value=7
i=1 value=7
i=2 value=7
i=3 value=7
i=4 value=7

For convenience of use of user functions, it is allowed to group and put them into individual files. These files, if necessary, should be included by using the directive #include "folder\filename".

Example:
Let there be a compiled io.ntl file , which is located in the Advisors folder:

void Print(array <int> a, string separator=" ")
{
 	string data="";
 	for(uint i=0;i<a.length();i++)
 	{
 	  data+=a[i];
 	  if(i<a.length()-1) data+=separator;
 	} 	
 	System.Print(data);
}

The script ArrayExample.ntl uses the Print function, defined in io.ntl:

#include "Advisors\io.ntl"
int Initialize()
{
	return(0);
}
int Run()
{
	array<int> a = {22,11,33};
	Print(a);
	return(0);
}
int DeInitialize()
{
	return(0);
}