# Optimizations for bubble sort

The code performs bubble sort on the basis if any swaps has been performed in the iteration. I made it sort of independent of number of iterations as in any conventional bubble sorting code.

I went on pretty much with what I understood from the cs50 class. This mechanism looks more intuitive to me. What improvements I need to do on the design/style/method?

#include<stdio.h>

void printMyArray(int a[],int n);

//BUBBLE SORT
int main(){
int a[] = {-1 , 2 , 0 , -3 , 5 , 1};
int n = 6;
for(;;){

int swap = 0;
int i = 0;

for(; i < n-1; i++)
if( a[i+1] <= a[i]){
int temp = a[i+1];
a[i+1] = a[i];
a[i] = temp;
swap = 1;
}
if(swap == 0)
break;
}
printMyArray(a,6);

}
void printMyArray(int a[],int n){
int i;
for(i = 0; i < n ; i++)
printf("%d\t",a[i]);
printf("\n");
}

• One obvious optimization: Don't use bubblesort! – Edward May 8 '16 at 22:05
• I get the point but I am asking in terms of improving the above scenario. – piepi May 8 '16 at 22:11

Function

1. Certainly no reason to swap when values are equal. In worse case of array {3,3,3,3}, leads to infinite loop.

//if( a[i+1] <= a[i]){
if(a[i+1] < a[i]) {

2. Use size_t to index arrays.

// void printMyArray(int a[],int n){
void printMyArray(int a[], size_t n) {


Style

1. Rather than int for Boolean variables use bool.

#include <stdbool.h>

// int swap = 0;
bool swap = false;

2. Recommend const when able. Adds clarity to the function and allows for optimizations with some compilers.

// void printMyArray(int a[],int n){
void printMyArray(const int a[], int n) {

3. Minor: prefer int *a rather than int a[] as argument in printMyArray().

4. More useful to separate main() from the code under test. Something like:

int main(void) {
int a[] = {-1 , 2 , 0 , -3 , 5 , 1};
bubble_sort(a, sizeof a/ sizeof a);
printMyArray(a, sizeof a/ sizeof a);
return 0;
}

5. Suggest fully {} blocks. Use Idiomatic for(), Avoid n-1, as size_t n may be 0.

   // int i = 0;
// for(; i < n-1; i++)

for(size_t i = 1; i < n; i++) {
if(a[i] < a[i-1]) {
int temp = a[i];
a[i] = a[i-1];
a[i-1] = temp;
swap = 1;
}
}

• Thanks for pointing out the bug though. – piepi May 9 '16 at 1:05