Optimizations for bubble sort

Question

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");
}

• Edward: One obvious optimization: Don't use bubblesort!
• piepi: I get the point but I am asking in terms of improving the above scenario.

Answer 1

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[0]);
    printMyArray(a, sizeof a/ sizeof a[0]);
    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;
    }
    }