Implementation of bubble sorting algorithm

// implementation of bubble sorting algorithm
// @author: fueanta
// Date: Fri 7, Oct 2016

#include "cstdio"

template <typename T>
void interchange(T &, T &);

void asc(double*, int);
void desc(double*, int);

int main() {
    int sizeu; printf("Size of the array please: "); scanf("%d", &sizeu);
    double arr[sizeu];
    printf("\nNow, give the elements of the array:\n");
    for (int i= 0; i < sizeu; i++) {
        printf("\nElement at index no[%d]: ", i);
        scanf("%lf", &arr[i]);
    }
    printf("\n\nArray in ascending order.....\n");
    asc(arr, sizeu);
    for (int i = 0; i < sizeu ;i++) {
        printf("\nElement at index no[%d]: |%.2lf|\n", i, arr[i]);
    }
    printf("\n\nArray in descending order.....\n");
    desc(arr, sizeu);
    for (int i = 0; i < sizeu ;i++) {
        printf("\nElement at index no[%d]: |%.2lf|\n", i, arr[i]);
    }
    return 0;
}

template <typename T>
void interchange(T &x, T &y) {
    T temp = x;
    x = y;
    y = temp;
}

void asc(double arr[], int n) {
    for (int i = 0; i < n-1 ; i++) {
        bool flag = false;
        for (int j = 0; j < n-1 ; j++) {
            if (arr[j] > arr[j+1]) {
                interchange(arr[j], arr[j+1]);
                flag = true;
            }
        }
        if (flag == false)
            break;
    }
}

void desc(double arr[], int n) {
    for (int i = 0; i < n-1 ; i++) {
        bool flag = false;
        for (int j = 0; j < n-1 ; j++) {
            if (arr[j] < arr[j+1]) {
                interchange(arr[j], arr[j+1]);
                flag = true;
            }
        }
        if (flag == false)
            break;
    }
}