Bubble Sort + Binary Search

#include "cstdio"

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

void sort_asc(int arr[], int);
int bi_search(int arr[], int, int);

int main() {
    int sizeu; printf("Give Array Size: "); scanf("%d", &sizeu);
    int arr[sizeu];
    for (int i = 0; i < sizeu ; i++) {
        printf("\nElement at index %d: ", i);
        scanf("%d", &arr[i]);
    }
    printf("\nGiven Array: \n");
    for (int i = 0; i < sizeu ; i++) {
        printf("\nElement at index %d: %d", i, arr[i]);
    }

    printf("\n\nAscending array elements....\n");
    sort_asc(arr, sizeu);
    for (int i = 0; i < sizeu ; i++) {
        printf("\nElement at index %d: %d", i, arr[i]);
    }

    printf("\n\nWhich element do you wish to search? : "); int item; scanf("%d", &item);
    int position = bi_search(arr, sizeu, item);
    if ( position != -1 )
        printf("\nElement has found at index no %d.", position);
    else
        printf("\nElement could not be found.");
    printf("\n");

    return 0;
}

void sort_asc(int 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;
    }
}

int bi_search(int arr[], int n, int desired) {
    int first = 0, last = n-1, position = -1;
    bool found = false;
    while (found != true && first <= last) {
        int mid = (first+last)/2;
        if (arr[mid] == desired) {
            found = true;
            position = mid;
        }
        else if (arr[mid] > desired)
            last = mid - 1;
        else
            first = mid + 1;
    }
    return position;
}