Bubble Sort in C - c

Question

I am trying to implement Bubble sort in C and have come this far but its nor sorting properly.
#include<stdio.h>
int main()
{
int n, i, j, a[5], b, temp;
printf("Enter the number of elements to be sorted\n");
scanf("%d", &n);
for(i = 0; i < n; ++i)
{
printf("%d - Enter the elements - ", i);
scanf("%d", &a[i]);
}
for(i = 0; i < n; ++i)
{
for(j = 0; j < n+1; ++j)
{
if(a[i] > a[i+1])
{
temp = a[i];
a[i] = a[i+1];
a[i+1] = temp;
}
}
}
for (i = 0; i < n; ++i)
{
printf("%d\n", a[i]);
}
return 0;
}
Input
2
12
1
13
Output
2
1
12
13
What am I missing ?

Answer 1

So now that the drama is behind us, the problem with your code was that you were not using the proper index in your inner loop. In addition your inner loop counter's conditional check was not correct. Also, as I mentioned in a comment to your question, you have a flaw in your code (which I have not fixed) where you initialize your array prior to asking the user how many elements they want to enter. This can lead to an index out of bounds exception if the user enters a number greater than 5.
#include<stdio.h>
int main()
{
int n, i, j, a[5], b, temp;
printf("Enter the number of elements to be sorted\n");
scanf("%d", &n);
for(i = 0; i < n; ++i)
{
printf("%d - Enter the elements - ", i);
scanf("%d", &a[i]);
}
for(i = 0; i < n; i++)
{
for(j = 0; j < n-1; j++)
{
if(a[j] > a[j+1])
{
temp = a[j];
a[j] = a[j+1];
a[j+1] = temp;
}
}
}
for (i = 0; i < n; ++i)
{
printf("%d\n", a[i]);
}
return 0;
}

Answer 2

your second loop is not proper.
for(j=0;j<n-i-1;j++){
}

Answer 3

/*By your approach , in inner loop you are not checking the each elements . So change i to j in swapping , and limit of j should be till n-1*/
#include<stdio.h>
int main()
{
int n, i, j, a[10], b, temp=0;
printf("Enter the number of elements to be sorted\n");
scanf("%d", &n);
for(i = 0; i < n; ++i)
{
printf("%d - Enter the elements - ", i);
scanf("%d", &a[i]);
}
for(i = 0; i < n; ++i)
{
for(j = 0; j < n-1; ++j) // notice limit , also complexity can be reduced by changing to(j<n-i-1)
{
if(a[j] > a[j+1])
{
temp = a[j]; // changed variable
a[j] = a[j+1];
a[j+1] = temp;
}
}
}
for (i = 0; i < n; ++i)
{
printf("%d\n", a[i]);
}
return 0;
}

Answer 4

/*You May check this code it will help you*/
#include<stdio.h>
void bubble_sort(int a[],int n);
void bubble_sort(int a[],int n)
{
int i,j;
int temp;
for(i=0;i<n;i++)
{
for (j=0; j<=n-i-1;j++)
{
if (a[j]>a[j+1])
{
temp = a[j];
a[j] = a[j+1];
a[j+1] = temp;
}
}
}
}
main()
{
int a[10];
int i,n;
printf("Enter the number\n");
scanf("%d",&n);
printf("Enter the number\n");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
bubble_sort(a,n);
printf("sorted elements are\n");
for(i=0;i<n;i++)
printf("%d\n",a[i]);
}

Answer 5

#include<stdio.h>
int main()
{
int n, i, j, a[5], b, temp;
printf("Enter the number of elements to be sorted\n");
scanf("%d", &n);
for(i = 0; i < n; ++i)
{
printf("%d - Enter the elements - ", i);
scanf("%d", &a[i]);
}
for(i = 0; i < n; ++i)
{
for(j = 0; j < n; ++j)
{
if(a[j] > a[j+1]) //change the varible instead of i to j
{
temp = a[j];
a[j] = a[j+1];
a[j+1] = temp;
}
}
}
for (i = 0; i < n; ++i)
{
printf("%d\n", a[i]);
}
return 0;
}

Answer 6

I've tried to cover all possible conditions to reduce passes and comparisons for bubble sort to reduce the overall time taken. Here goes my code...
#include <stdio.h>
#include <conio.h>
void bubbleSort(int n){
int arr[n],i,j,temp=0;
int swapFlag = 0;
printf("\nInsert %d elements:\n",n);
for(i=0;i<n;i++){
scanf("%d",&arr[i]);
}
printf("Insert complete.\n\n");
printf("Your array looks like:\n");
for(i=0;i<n;i++){
printf("%d ",arr[i]);
}
//Bubble Sort Algorithm
for(i=0;i<n-1;i++){
swapFlag = 0;
for(j=0;j<n-i-1;j++){
if(arr[j]>arr[j+1]){
swapFlag = 1;
//Swapping unordered pairs
temp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = temp;
}
}
//Condition to reduce number of passes & comparisons
if(swapFlag == 0){
break;
}
}
printf("\n\nAfter sorting the array looks like:\n");
for(i=0;i<n;i++){
printf("%d ",arr[i]);
}
}
void main(){
int n;
printf("Enter number of array elements: ");
scanf("%d",&n);
bubbleSort(n);
getch();
}
Result:-