Can i define a substitution of the repeated name of an array ?

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hello , i have this fuction to grow an array and return its latest element for immediate access :

//expand primitive array
template<typename X>
int expand_primitive_array(X &array[]){
ArrayResize(array,ArraySize(array)+1,0);
return(ArraySize(array)-1);
}

template<typename X>
int last_element_index(X &array[]){
return(ArraySize(array)-1);
}

I can't return a pointer to a primitive array element.

but i can do this :

  int primitive[];
  primitive[expand_primitive_array(primitive)]=5;

its not a problem , just wondering is there a macro substititution i can use to do something like 

primitive[grow_and_use_last]=5;

thank you 

 
Lorentzos Roussos:

hello , i have this fuction to grow an array and return its latest element for immediate access :

I can't return a pointer to a primitive array element.

but i can do this :

its not a problem , just wondering is there a macro substititution i can use to do something like 

thank you 

Yes, you can:


#define grow_and_use_last(x)    x[expand_primitive_array(x)]

int primitive[];
grow_and_use_last(primitive) = 5;
 
Lorentzos Roussos: just wondering is there a macro substititution i can use to do something like
Always prefer actual functions to macros. 
template<typename X>
void addToArray(X& array[], X value){
   int iEnd=ArraySize(array); ArrayResize(array, iEnd+1); Array[iEnd]=value;
}

That makes sure the value added is, or can be converted to, the proper type.

 
William Roeder #:
Always prefer actual functions to macros.

That makes sure the value added is, or can be converted to, the proper type.

I would suggest to extend the functionality, so the replacement is function-compatible with the macro:

template <typename X>
const X addToArray(X& array[], const X new_value)
{
        const int new_value_ptr = ArraySize(array);
        ArrayResize(array, new_value_ptr + 1);
        array[new_value_ptr] = new_value;
        return(new_value);
};
 
Dominik Christian Egert #:

Yes, you can:


thanks

William Roeder #:
Always prefer actual functions to macros.

That makes sure the value added is, or can be converted to, the proper type.

thanks

edi: 

wasn't there a macro that read the name of the variable ? 

 
Lorentzos Roussos #: wasn't there a macro that read the name of the variable ? 

Do you mean this? ...

Forum on trading, automated trading systems and testing trading strategies

any way to store expression into a variable or array?

Fernando Carreiro, 2022.08.18 21:03

There is also a way of using macros to "stringify" the expression, so that you don't have to type the expression twice. This will help keep the code consistent when you update the expressions.

However, this is a more power programmer coding skill that needs careful planing of the code logic, but you can research the "#" Stringification functionality of the standard C/C++ preprocessor which also works on MQL.


 
Fernando Carreiro #:

Do you mean this? ...


ah yes , thank you . 

 

Yes, you can define a macro substitution to achieve the functionality you're looking for. Here's an example of how you could define such a macro:

#define GROW_AND_USE_LAST(arr, val) arr[expand_primitive_array(arr)] = val;

With this macro, you can simply use the following code to grow the array and set the value of the last element:

GROW_AND_USE_LAST(primitive, 5);

This will expand the primitive array and set its last element to the value 5.

Note that this macro uses the function expand_primitive_array that you provided in your code.


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Bogdan Ion Puscasu #:

Yes, you can define a macro substitution to achieve the functionality you're looking for. Here's an example of how you could define such a macro:

#define GROW_AND_USE_LAST(arr, val) arr[expand_primitive_array(arr)] = val;

With this macro, you can simply use the following code to grow the array and set the value of the last element:

GROW_AND_USE_LAST(primitive, 5);

This will expand the primitive array and set its last element to the value 5.

Note that this macro uses the function expand_primitive_array that you provided in your code.


Thanks , that is very compact .

Ps : i like how seo optimized your reply is  😊

 
Lorentzos Roussos #:

...

Ps : i like how seo optimized your reply is  😊

I don't get it, what do you mean ?

 
Alain Verleyen #:

I don't get it, what do you mean ?

Google will rank a page higher if it finds the form :

Can i do X? (in the header)

  • Yes, you can do X by .... (as much of the question present in the answer possible)
  • No, you cannot do X ... 

Because it makes more sense to the user and it means they can potentially find what they searched for.

If "Yes, you can do X by ..." is garbage however , the user will return to google , and the page will be penalized.

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