segregate_even_and_odd_elements_on_an_array_v2.c

/*

    segregate_even_and_odd_elements_on_an_array_v2.c

https://www.w3resource.com/c-programming-exercises/array/c-array-exercise-96.php


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include<stdio.h>

// Displays the array arr[n] of n integers with text before and after the array
void print_array(char *text_before, int arr[], int n, char *text_after){
    printf("%s", text_before);
    for(int i=0;i<n;i++)
        printf("%3d",arr[i]);
    printf("%s", text_after);
}

// Displays one element of the array arr[n] of n integers on it's place
void print_one_element_of_array_on_its_place(char *text_before, int arr[], int n,
                                            int index, char *text_after){
    print_array("\n",arr,n,"\n");
    printf("%s", text_before);
    for(int i=0;i<n;i++)
        if(i==index)
            printf("%3d",arr[i]);
        else
            printf("%3s"," ");
    printf("%s", text_after);
}

// Displays two elements of the array arr[n] of n integers on theirs place
void print_two_elements_of_array_on_theirs_place(char *text_before, int arr[], int n,
                                                int index1, int index2, char *text_after){
    print_array("\n",arr,n,"\n");
    printf("%s", text_before);
    for(int i=0;i<n;i++)
        if(i==index1 || i==index2)
            printf("%3d",arr[i]);
        else
            printf("%3s"," ");
    printf("%s", text_after);
}

void changePlace(int *ar, int *br){
    int temp = *ar;
    *ar = *br;
    *br = temp;
}

void EvenOddSegre(int arr[], int n){
    int l_index = 0, r_index = n-1;

    while (l_index < r_index){
        while (arr[l_index]%2 == 0 && l_index < r_index){
            printf("\n left index: %2d , right index: %2d \n",l_index,r_index);
            print_one_element_of_array_on_its_place("",arr,n,l_index,"\n");
            printf("\n arr[%d] = %d is even, so we go to the right to the next element of the array. \n",l_index,arr[l_index]);
            l_index++;
        }

        while (arr[r_index]%2 == 1 && l_index < r_index){
            printf("\n left index: %2d , right index: %2d \n",l_index,r_index);
            print_one_element_of_array_on_its_place("",arr,n,r_index,"\n");
            printf("\n arr[%d] = %d is odd, so we go to the left to the previous element of the array. \n",r_index,arr[r_index]);
            r_index--;
        }

        if (l_index < r_index){
            printf("\n left index: %2d , right index: %2d \n",l_index,r_index);
            print_two_elements_of_array_on_theirs_place("",arr,n,l_index,r_index,"\n");
            printf("\n We exchange elements  arr[%d] = %d  and  arr[%d] = %d  with each other. \n",
                    l_index, arr[l_index],  r_index, arr[r_index] );
            changePlace(&arr[l_index], &arr[r_index]);
            print_array("\n",arr,n,"\n");
            l_index++;
            r_index--;
        }
    }
}


int main()
{
    int arr[] = {17, 42, 12, 19, 7, 27, 24, 30, 54, 73};
    int n = sizeof(arr)/sizeof(arr[0]);

    print_array("\n The given array is: \n\n",arr,n,"\n");

//  print_one_element_of_array_on_its_place("",arr,n,1,"\n");

//  print_two_elements_of_array_on_theirs_place("",arr,n,2,5,"\n");

    EvenOddSegre(arr, n);

    print_array("\n The array after segregation is: \n\n",arr,n,"\n\n");

    return 0;
}