How to create my own operator(something like +) in any programming language?

Answer 1

Kotlin code:
// Provide this[index] access to the list for read access.
operator fun get(index: Int) = list[index]
// Provide this[index] access to the list for write access.
operator fun set(index: Int, value: Int) {
list[index] = value
}

C++ code:
// Provide this[index] access for read/write.
int& operator[](const int index) {
    return list[index];
}

Python code:
// Provide this[index] access to the list for read access.
def __getitem__(self, index):
return self.list[index]
// Provide this[index] access to the list for write access.
def __setitem__(self, index, value):
self.list[index] = value

Answer 2

Ideally you'd use functions. i.e, to cube a number:

function cbrt(num){
return Math.pow(num, 3);
}
console.log(cbrt(5));
//prints 125 to the console

As for actual operators such as + or -, I don't think this is possible.