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techInterview Discussion

I was reading the book, "Find the bug" by Adam Barr.

An interesting concept, where you are shown code and you have to find bugs in it.

Here is one in C:

/* Selection Sort */

void sort (int a [] , int n /*length*/) {

  int current, j, lowestindex, temp;

  for (current = 0; current < n -1; current++) {

    lowestindex = current;

    for (j = current+1; j < n; j++) {

      if (a[j] < a[current]) {
        lowestindex = j;
      }

    } /* inner for */
   
    if (lowestindex != current) {
      temp = a[current];
      a[current] = a[lowestindex];
      a[lowestindex] = tmp;
    }

  } /* outer for*/
}

j < n

temp is misspelled tmp (not sure if that's a transcription error).

I have the book. It is a transcription error.

Oh, cute.

(It's not j < n.)

The loop to find lowestindex always compare to current, and so it will find the last (not lowest) index whose value is less than current.
Proper would be:

lowestindex = current;

    for (j = current+1; j < n; j++) {

      if (a[j] < a[lowestindex]) {
        lowestindex = j;
      }

That is right Radu. Subtle, and very plausible.

int n /*length*/ should be int length

but then I'm one of those IfYouFeelTheNeedToWriteACommentTryToRefactorInstead guys ;)

I believe it was Myopic's attempt to make the problem a little more clearer. The book does not have the length comment. So, don't judge the book by the errors in the original post, please.