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));
    }
}

`sortodd(&ptr, ev, od, n, &ptreven); } int sortodd(int *ptr, int ev, int od, int n, int ptreven)` : The type of `ptr` and `ptreven` are different. `merge(&ptr, ev, od, n, &ptreven, &ptrodd); } int merge(int *ptr, int ev, int od, int n, int *ptreven, int *ptrodd)` : ditto. and so on. — BLUEPIXY, Dec 17 '16 at 14:31
your program has multiple logical and programmatical issues. e.g. (ptr+i), ptr is pointer to integer, i is an integer, how do you wanna do that operation. plus, it is not bad to check the warning at compile level, they give you good information. Yo repeated this operation a lot in your code. first fix simple mistakes then put the corrected code here to find the logical problem to it. I think your problem is not understanding how pointer works — Eisa, Dec 17 '16 at 14:34
@SyedHussain you can use `qsort` for this, it would make your code alot shorter. — RoadRunner, Dec 17 '16 at 15:43
The point of this being given to you as homework is so you learn how to use tools like the compiler to help you write your code. Read the advice given to you by @Eisa and follow it. Once you have code that compiles without warnings then ask for human help. Or ask for human help to fix specific compiler errors and/or warnings. If that approach is distasteful to you then you should stop attending your programming class now because that's what programming is and you need to get used to it or stop doing it. — jwpfox, Dec 18 '16 at 04:08

score 1 · Answer 1 · answered Dec 17 '16 at 16:14

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');
}

sorting program using pointers

1 Answers1