How do you set a variable comparison operator that can be used as conditions in loops such as for loop?

Question

Currently, I have a code that relies on the concept of having to use either an increment or decrement for the for loop depending on a certain condition. Example would be two tact switches for Arduino. One would trigger the positive increment and the other for the negative increment.

int inc; //Increment that is +1 or -1
int limit; //Minimum value for decrement and maximum value for increment

void loop() {
    if(CONDITION) { //Condition for positive increment
        i = 1;
        limit = 15;

        for(int i = 0; i <= limit; i = i + inc) {
            //Statements
        }
    } else { //Condition for negative increment
        i = -1;
        limit = 0;
        for(int i = 0; i >= limit; i = i + inc) {
            //Statements
        }
    }
}

I want to make a uniform code for both situations where you just change a parameter, such as the variable. Now I have no problem with changing the increment. Just set a variable that becomes positive or negative 1. The same goes for the minimum and maximum values. My problem is the comparison operator.

Now I've done some searching myself but can't quite understand how to apply what I've read for this situation I've mentioned here. I will reference the links here.

Is there a way to make a comparison operator a variable?

Are Variable Operators Possible?

My big issue is none of the content in those links as far as from what I can recall have applied a comparison operator inside a loop such as for. Is there a way to create a variable operator of sorts for the situation I have stated? My goal is to be able to remove the for statements inside the if else conditions I have created and move it outside. I would instead put inside the if else conditions the code that would allow me to set the comparison operators <= and >=. Here is an idea of what I would want it to look like.

int inc; //Increment that is +1 or -1
int limit; //Minimum value for decrement and maximum value for increment

void loop() {
    if(CONDITION) { //Condition for positive increment
        i = 1;
        limit = 15;
        /*
        (Code to make the operator <=)
        Wrong code technically but the concept would be
        VariableOperator = <=
        */
    } else { //Condition for negative increment
        i = -1;
        limit = 0;
        /*
        (Code to make the operator >=)
        Wrong code technically but the concept would be
        VariableOperator = >=
        */
    }
    
    for(int i = 0; /* i VariableOperator limit */; i = i + inc) {
        //Statements
    }
}

Though this is just a concept because I have no idea on how it would work. The code would probably be different. I really don't have an idea.

Answer 1

There are many ways you could do this in C++, with varying complexity.

But the very simplest and clearest (in my opinion) is:

const int limit = 15;
for (int i = 0; i <= limit; ++i)
{
    int index = (inc > 0 ? i : limit - i);
    // Now use index instead of i
}

I have made a bit of a stretch here, assuming that all you want to do is loop 16 times (either counting from 0 to 15 or 15 to 0). It wasn't completely clear from your code, because it was full of errors and you never actually described in simple terms what you want.

Please note that your non-standard indentation style makes your code quite difficult to read. Maybe you like Python, but this is not how we do it in C++. Edit: question has since been edited to fix indentation, but I will leave this comment for the benefit of author.