here is the code, you need to write a function to flip the array backwards, please help example: (the first element is swapped with the last, the second with the penultimate)

I tried to create an array inside the function, but I didn't understand what to write in the body if you can help, I will be very grateful

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <locale.h>
void scan(int* , size_t );

void print(int* , size_t );


int get_max(int* , size_t );


int get_min(int* , size_t );


void invert(int*, size_t);


float get_average(int* , size_t);


void turn(int* , size_t );


int main()
    {
    setlocale(LC_ALL, "Russian");
    size_t n;
    printf("Введите размер массива: ");
    scanf("%llu", &n);
    int* bebra = (int*)calloc(n, sizeof(int));
    scan(bebra, n);
    print(bebra, n);
    int max = get_max(bebra, n);
    printf("Значение максимального элемента: %d\n", max);
    int min = get_min(bebra, n);
    printf("Значение минимального  элемента: %d\n", min);
    float avg = get_average(bebra, n);
    printf("Средне арифметическое значение:  %f\n", avg);
    invert(bebra, n);
    print(bebra, n);
    }

void scan(int* a, size_t n)
    {
    printf("Ввод массива: \n");
    for (size_t i = 0; i < n; i  )
        {
        printf("arr[%llu] = ", i);
        scanf("%d", &a[i]);
        }
    }


void print(int* a, size_t n)
    {
    printf("Печать массива: \n");
    for (size_t i = 0; i < n; i  )
        {
        printf("arr[%llu] = %d\n", i, a[i]);
        }
    }


int get_max(int* a, size_t n)
    {
    int max = INT_MIN;
    for (size_t i = 0; i < n; i  )
        {
        if (max < a[i])
            {
            max = a[i];
            }
        }
    return max;
    }


int get_min(int* a, size_t n)
    {
    int min = INT_MAX;
    for (size_t i = 0; i < n; i  )
        {
        if (min > a[i])
            {
            min = a[i];
            }
        }
    return min;
    }


void invert(int* a, size_t n)
    {
    for (size_t i = 0; i < n; i  )
        {
        a[i] = a[i] * -1;
        }
    }


float get_average(int* a, size_t n)
    {
    float sum = 0;
    for (size_t i = 0;i < n;i  )
        {
        sum = sum   a[i];
        }
    return sum / n;
    }

CodePudding user response：

I think this should work :)

void flip(int * array, size_t length)
{
        for (int i = 0; i < length / 2;   i) {
                int backwards_index = length - 1 - i;
                
                int array_at_index = array[i];
                array[i] = array[backwards_index];
                array[backwards_index] = array_at_index;
        }
}

The code swaps elements from the front and the back of the array, one by one. i will loop through half the values in array, rounded down (if there is a middle element, it doesn't matter if it's swapped with itself or not). If i iterated through the entire array, the elements would be swapped twice and the array wouldn't change.

backwards_index will be the index of the i'th element of the array from the back. Since the element in the array ranges from 0 to length - 1, inclusive, this element should have an index of length - 1 when i is 0 and count backwards (aka subtract i). Then, the values of the i'th element from the front and the back of the array are swapped.

Hope it helps!

CodePudding user response：

int *flip(int *arr, const size_t length)
{
    int *start = arr, *end = arr   length - (1 & (!!length));

    while(start < end)
    {
        int tmp = *start;
        *start   = *end;
        *end-- = tmp;
    }
    return arr;
}