Sort numeric array using bubble sort

This program sorts the array a[] using bubble sort method.In bubble sorting,every value of the array is compared sequentially and temporary variable t is used for sorting the values.

-Initially,n different values are placed in constant array with sufficient large size.

-Here,the comparison starts from bottom position(0) and in each iteration the smallest bubble is shifted upward.

-Each comparison starts from bottom position by using the values from 2 positions (0 and 1). After comparision the smallest value is placed in position 1.Then the values from next 2 positions (1 and 2) are used.After comparison the smallest value is placed in position 2.This process continous in upward direction.

-In first iteration,the smallest value is placed in position (n-1).

-In second iteration,the smallest value is placed in position (n-2).

-In third iteration,the smallest value is placed in position (n-3).

-In last iteration,the last smallest value is placed at n th position i.e. at the bottom.

#include < stdio.h >
#include < conio.h > 

void main()
{
    int a[20],t;
     int i,j,n;
     clrscr();
     printf("\nEnter n :");
     scanf("%d",&n);
     printf("\nEnter %d values \n",n);
     for(i=0;i < n;i++)
    {
        scanf("%d",&a[i]);
    }
    printf("\n%d values before sorting are \n",n);
    for(i=0;i < n;i++)
    {
        printf("%4d",a[i]);
    }
    bubble_sort(a,n);
    printf("\n%d values after sorting are \n",n);
    for(i=0;i < n;i++)
    {
        printf("%4d",a[i]);
    }
}

int bubble_sort(int a[],int n)
{
    int i,j,k;
    int t;

    for(k=n;k>=1;k--)
    {
        for(i=0,j=1;j < =k;i++,j++)
        {
                if (a[j] < a[i])
                {
                    t=a[i];
                    a[i]=a[j];
                    a[j]=t;
                }
        }
    }
    return;
}