C++: Make the largest number from the array of elements.

Here is a C++ program where you are given an array of numbers. Append each element one after another in a way that the resulting number is the largest possible number you can make out of all the given array elements.

	#include<iostream>
	#include<vector>
	#include<string>
	#include <bits/stdc++.h>
	using namespace std;
	void printArray(int arr[], int n);
	void rearrangeArray(int arr[], int n);
	long append(int arr[], int n);
	bool firstDigitLarger(int a, int b);
	bool firstDigitLarger(int a, int b) {
	int aFirst, bFirst, digit1, digit2;
	while(a != 0) {
	digit1 = a;
	a /= 10;
	}
	aFirst = digit1;
	while(b != 0) {
	digit2 = b;
	b /= 10;
	}
	bFirst = digit2;
	return aFirst > bFirst;
	}
	long append(int arr[], int n) {
	string appended;
	for(int i = 0; i<n; i++) {
	std::string base = std::to_string(arr[i]);
	appended += base;
	}
	return std::stol(appended);
	}
	void rearrangeArray(int arr[], int n) {
	sort(arr, arr+n, greater<int>());
	sort(arr, arr+n, firstDigitLarger);
	}
	void printArray(int arr[], int n) {
	for(int i = 0; i< n; i++) {
	cout<<arr[i]<<" ";
	}
	}
	int main() {
	int arr[] = {546,548,60,9,696};
	int n = sizeof(arr)/sizeof(arr[0]);
	rearrangeArray(arr,n);
	cout<<append(arr,n);
	return 0;
	}

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Output: 969660548546