sorting program using pointers

Question

I have a program that:

• given a sequence of numbers,
• sorts even numbers in ascending order, and
• sort odd numbers in descending order, and
• adds the sorted even numbers to an array followed by the sorted odd numbers.

Example:

Input: 1, 2, 3, 4, 5, 6  
Expected output: 2, 4, 6, 5, 3, 1  
Actual output: 1578032, 0, 3, 6, 6487408, 0   

here is my code:

#include < stdio.h >

int main() {
    input();
}
int input() {
    int n;
    printf("Enter The Number Of Elements You Want To Enter : ");
    scanf("%d", & n);
    int * ptr, i, ev = 0, od = 0;
    ptr = (int * ) calloc(n, sizeof(int));
    for (i = 0; i < n; i++) {
        printf("Enter Number : ");
        scanf("%d", (ptr + i));
        if ( * (ptr + i) % 2 == 0) {
            ev++;
        } else {
            od++;
        }
    }

    sorteven( & ptr, ev, od, n);
}
int sorteven(int * ptr, int ev, int od, int n) {
    int i, j = 0, swap = 0, * ptreven;
    ptreven = (int * ) calloc(ev, sizeof(int));
    for (i = 0; i < n; i++) {
        if ( * (ptr + i) % 2 == 0) { *
            (ptreven + j) = * (ptr + i);
            j++;
        }
    }
    for (i = 0; i < ev - 1; i++) {
        for (j = 0; j < ev - i - 1; j++) {
            if ( * (ptreven + j) > * (ptreven + j + 1)) {
                swap = * (ptreven + j); *
                (ptreven + j) = * (ptreven + j + 1); *
                (ptreven + j + 1) = swap;
            }
        }
    }
    sortodd( & ptr, ev, od, n, & ptreven);
}
int sortodd(int * ptr, int ev, int od, int n, int ptreven) {
    int i, k = 0, swap = 0, * ptrodd, j;
    ptrodd = (int * ) calloc(od, sizeof(int));
    for (i = 0; i < n; i++) {
        if ( * (ptr + i) % 2 != 0) { *
            (ptrodd + k) = * (ptr + i);
            k++;
        }
    }
    for (i = 0; i < od - 1; i++) {
        for (j = 0; j < od - i - 1; j++) {
            if ( * (ptrodd + j) < * (ptrodd + j + 1)) {
                swap = * (ptrodd + j); *
                (ptrodd + j) = * (ptrodd + j + 1); *
                (ptrodd + j + 1) = swap;
            }
        }
    }
    merge( & ptr, ev, od, n, & ptreven, & ptrodd);
}
int merge(int * ptr, int ev, int od, int n, int * ptreven, int * ptrodd) {
    int * ptrmerge, i, j;
    ptrmerge = (int * ) calloc(n, sizeof(int));
    for (i = 0; i < ev; i++) { *
        (ptrmerge + i) = * (ptreven + i);
    }
    for (i = ev, j = 0; i < n; i++, j++) { *
        (ptrmerge + i) = * (ptrodd + j);
    }
    display( & ptrmerge, n);
}
int display(int * ptrmerge, int n) {
    int i;
    printf("OUTPUT : ");
    for (i = 0; i < n; i++) {
        printf(" %d ", * (ptrmerge + i));
    }
}

Answer 1

like this

#include <stdio.h>
#include <stdlib.h>

void input(void);

int main(void){
    input();
}

void sorteven(int *ptr, int n);
void sortodd(int *ptr, int n);
void display(int *ptt, int n);

void input(void){
    int n;
    printf("Enter The Number Of Elements You Want To Enter : ");fflush(stdout);
    scanf("%d", &n);

    int *ptr, i, ev = 0, od = 0;
    if((ptr = calloc(n, sizeof(int)))==NULL){
        perror("malloc");
        exit(EXIT_FAILURE);
    }

    for (i = 0; i < n; i++){
        int v;
        printf("Enter Number : ");fflush(stdout);
        scanf("%d", &v);

        if(v % 2 == 0){
            ptr[ev++] = v;
        } else {
            ptr[n - ++od] = v;
        }
    }

    sorteven(ptr, ev);
    sortodd(ptr + ev, od);
    display(ptr, n);
    free(ptr);
}

void sorteven(int *ptr, int n){
//sort to ascending order
    int i, j, temp;

    for (i = 0; i < n - 1; i++){
        for (j = 0; j < n - i - 1; j++){
            if(ptr[j] > ptr[j + 1]){
                int temp = ptr[j];
                ptr[j] = ptr[j + 1];
                ptr[j + 1] = temp;
            }
        }
    }
}

void sortodd(int *ptr, int n){
//sort to descending order
    int i, j, temp;

    for (i = 0; i < n - 1; i++){
        for (j = 0; j < n - i - 1; j++){
            if(ptr[j] < ptr[j + 1]){
                int temp = ptr[j];
                ptr[j] = ptr[j + 1];
                ptr[j + 1] = temp;
            }
        }
    }
}

void display(int *ptr, int n){
    int i;

    printf("\nOUTPUT : ");
    for (i = 0; i < n; i++){
        if(i)
            putchar(' ');
        printf("%d", ptr[i]);
    }
    putchar('\n');
}