Trying to implement a simple one-time bubble sort in c++

Question

I'm trying to make a bubble sort. Here's what I have:

#include <iostream>
#include <vector>
using namespace std;

int main() {
    double small;
    double big;
    double i;
    vector<double>list;
    while(cin){
        cin>>i;
        list.push_back(i);
    }
    for(i=0;i<list.size()-1;i++){
        small=list[i];
        big=list[i+1];
        if(small<=big){
        }
        else{
            list[i]=big;
            list[i+1]=small;
        }
    }
    for(i=0;i<list.size()-1;i++)
        cout<<list[i]<<'\n';
    return 0;
}

Here's my input:

but it outputs this:

The expected output should be: 5,6,8,9,123,515,4141,12990,21378,231366.(Ignore this, I was being dumb, the output is correct besides for the duplicated number). Any help? Sorry if this trivial.

If by 'only goes through one-time' you mean one iteration of the sort, then your output is correct (however I think you wrote `9` twice there). If you mean something else, please explain it better. — Adalee, Jun 27 '15 at 22:25

score 0 · Answer 1 · answered Jun 27 '15 at 22:40

0

9 is read twice since you are using while(cin), it should be

while(cin >> i){
    list.push_back(i);
}

answered Jun 27 '15 at 22:40

Xiaotian Pei

3,210
21
40

score 0 · Answer 2 · answered Jun 27 '15 at 22:40

You are getting an extra 9 because it is the last thing you input and you are not breaking out of the loop correctly. Therefore you end up adding it to your list twice. Something like this is more appropriate:

while(cin>>i){
  list.push_back(i);
  cout << "Adding " << i << "\n";
}

In your previous cause you had the following:

while(cin){
    cin>>i; // <-- reaches the end of file
    list.push_back(i); // <-- puts something in the list even though we didn't read anything
}

Note that when cin reaches the EOF you will still add i to the list, which still has its old value as cin didn't read in any input besides EOF. The correct I have in the first code segment fixes this issue.

score 0 · Answer 3 · edited May 23 '17 at 11:58

0

Your input loop is running one too many times giving a duplicate element at the end of the list. If you change the while loop to be:

 while(cin >> i){
    list.push_back(i);
 }

then the last element is only added once. You will also need to change the bounds on the output loop.

See this question about while (cin)

edited May 23 '17 at 11:58

Community

1
1

answered Jun 27 '15 at 22:41

Ruth Franklin

365
3
2

jimifiki · Answer 4 · 2015-06-28T14:38:09.323

0

You have to run a nested loop

for(j=0;j<list.size()-1;j++){
    for(i=0;i<list.size()-1-j;i++){

right now you are moving 231366, the biggest number, to the end of the list. You have to iterate on.

edited Jun 28 '15 at 14:38

answered Jun 28 '15 at 14:32

jimifiki

5,377
2
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60

Trying to implement a simple one-time bubble sort in c++

4 Answers4