C++, function with changing amount of inputs (idk how to describe) - c++

Question

The funcion HIGHEST is all good and accepts variable number of arguments. The problem is how do I do variable amount of input? (idk what terms should be use to describe it, but examples should clear things up...)
/*cout << highest(n, A[0],A[1],A[2],A[3]) <<endl;
this is what I would like to achieve,
but with a change - the number of array changes with
the input file and n defines how many of these will be.
ex.: if n = 7 it needs to be (n, A[0],A[1],A[2],A[3], A[4], A[5], A[6])
*/
Duom.txt file if needed (i am now only working with 1st number 4 under it others will follow same/similar thing as 1st row they are not important now)
4
2008 5 2000.00 400.25
2010 5 4000.00 320.25
2009 9 3385.00 254.45
2008 6 1900.00 612.59
#include <iostream>
#include <iomanip>
#include <cmath>
#include <fstream>
#include <cstdarg>
using namespace std;
//Variable number of arguments in C++
int highest (int num,...) {
va_list valist;
int max = 0;
int a;
va_start(valist, num);
for (int i = 0; i < num; i++) {
a = va_arg(valist, int);
if(max < a) max = a;
else ;
}
va_end(valist);
return max;
}
int main () {
int n, A[25], B[25];
double C[25], D[25];
ifstream fd ("Duom.txt");
ofstream fr ("Rez.txt");
fd >> n;
cout << n <<endl;
for(int i = 0; i < n; i++){
fd >> A[i] >> B[i] >> C[i] >> D[i];
}
cout << highest(n, ) <<endl;
/*cout << highest(n, A[0],A[1],A[2],A[3]) <<endl;
this is what I would like to achieve,
but with a change - the number of array changes with
the input file and n defines how many of these will be.
ex.: if n = 7 it needs to be (n, A[0],A[1],A[2],A[3], A[4], A[5], A[6])
*/
return 0;
}

Answer 1

is there a specific reason you want the function Highest to get all array integers separately? Also - why did you choose to use an array instead of a vector?
Assuming that you want to use an array, I'd suggest to change the function's arguments as follows:
int highest (int num,int *arr);
where arr is the name of your array and in fact a pointer to the first integer of the array.
Then, inside the function, you can just access the array using subscript notation or dereferencing:
first_array_int=*(arr); //dereferencing example
second_array_int=*(arr+1); //dereferencing example
or
first_array_int=arr[0]; //subscript example
second_array_int=arr[1]; //subscript example
note that by doing that you can change the passed array within the function.
Again, I'd suggest to use a vector instead, then define the function:
int highest (int num,vector <int> *A);
if you want to pass a pointer, or:
int highest (int num,vector <int> A);
if you want to pass by value. Ofcourse, don't forget to include the vector library with
#include <vector>
I hope I understood your question well and that this is helpful.
Goodluck!
Guy