Selection sort on array in C - c

Question

I'm trying to create a simple(?) selection sort program in C that selects the largest integer of an integer array and places it in the location a[n-1], places the second largest number in a[n-2], etc until the smallest number is placed in a[0]. I've run through the below code on paper and it seems like it should work, but when I compile it I'm getting faulty results. Am I missing something obvious?
/* The program implements selection sort*/
#include <stdio.h>
#include "simpio.h"
#define n 5
void GetArray(int a[]);
void SelectionSort(int a[]);
int FindMax(int a[], int high);
void swap(int a[], int p1, int p2);
void PrintArray(int a[]);
main()
{
int a[n];
GetArray(a);
SelectionSort(a);
PrintArray(a);
getchar();
}
void GetArray(int a[])
{
int i;
for(i=0;i<n;i++)
{
printf("Enter integer# %d", i+1);
a[i]=GetInteger();
}
}
void SelectionSort(int a[])
{
int i, max;
for(i=0;i<n;i++)
{
max=FindMax(a,i);
swap(a,max,(n-1-i));
}
}
int FindMax(int a[], int high)
{
int i, index;
index=high;
for(i=high;i<n;i++)
{
if(a[i]>a[index])
index=i;
}
return index;
}
void swap(int a[], int p1, int p2)
{
int temp;
temp=a[p2];
a[p2]=a[p1];
a[p1]=temp;
}
void PrintArray(int a[])
{
int i;
for(i=0;i<n;i++)
printf("a[%d]=%d\n", i, a[i]);
}

Answer 1

Change these method to:
void SelectionSort(int a[])
{
int i, max;
for(i=0;i<n;i++)
{
max=FindMax(a,n-i-1);
swap(a,max,n-i-1);
}
}
int FindMax(int a[], int high)
{
int i, index;
index=high;
for(i=0;i<high;i++)
{
if(a[i]>a[index])
index=i;
}
return index;
}
I actually tested my answer and it works.

Answer 2

Selection sort is process of comparing minimum element from the list and placing from the least index.
Now consider below code snippet.
public void selectionSort(int[] elements) {
for(int i=0;i<elements.length;i++) {
int minPosition = i;
for(int j=i+1;j<elements.length;j++) {
if(elements[minPosition]>elements[j])
minPosition = j;
}
int temp = elements[i];
elements[i] = elements[minPosition];
elements[minPosition] = temp;
}
}
Thanks for reading, let me know feedback to improve from myside

Answer 3

Shouldn't:
max=FindMax(a,i);
swap(a,max,(n-1-i));
Be:
max=FindMax(a,i);
swap(a,max,i);
otherwise, next time through the loop, you'll find the same max value in the top position in the array.

Answer 4

A very basic implementation of selection sort
#include<stdio.h>
main()
{
int i,j,n=7,a[]={1,2,5,3,8,9,5},key;
for(j=1;j<n;j++)
{
key=a[j]; //a[j] is the new element to be added to the sorted
//sequence
i=j-1;
while(i>=0 && key<a[i]) //traverse through the sorted sequence
{a[i+1]=a[i];i--;} //until the place of key is found
a[i+1]=key;
}
for (j=0;j<n;j++)
printf("%d",a[j]);
}

Answer 5

#include<stdio.h>
#include<conio.h>
int removex(int arr[],int small,int n)
{
int i=0;
for(;i<n;i++)
if(arr[i]==small) //searching that no to delete
break;
for(;i<n-1;i++)
arr[i]=arr[i+1]; //delete by overloading no
return n-1;
}
void selectSort(int arr[],int sort[],int n)
{
int j=0,k=0,small;
while(n!=0)
{
small=arr[0];
for(j=0;j<n;j++)
if(arr[j]<small)
small=arr[j]; //finding smallest no
sort[k++]=small;
n=removex(arr,small,n); //removing that from list as we included that no into sorted list
}
}
void main()
{
int arr[10],arr2[10],i,n;
clrscr();
printf("Enter how many elements");
scanf("%d",&n);
for(i=0;i<n;i++)
scanf("%d",&arr[i]);
selectSort(arr,arr2,n);
printf("sorted list is\n");
for(i=0;i<n;i++)
printf("%d\n",arr2[i]);
getch();
}