Manipulating an Array

Question

I am new to C programming and I have an assignment that I am not even sure where to start. This is what I have to do: Take a List of integers and sort them into odds and evens putting the even integers to the back of the list in the order in which the occurred. And we have to return the number of even integers in the List[]

For example:

suppose the array list is initialized with Size set to 10:

int List[Size] = {13, 31, 24, 16, 3, 48, 21, 11, 39, 6};

Then a call to evensToBack() should result in

Index: 0 1 2 3 4 5 6 7 8 9

Value: 13 31 3 21 11 39 24 16 48 6 And the Value 4 being returned.

All with that all I am given is this starting piece of code:

`int evensToBack(int* const List, const int Size){
//body
}`

Please help explain to me how to get started here. I would greatly appreciate it.

Implement a plain sorting algorithm, but simply change the meaning of "less than" to mean "odd". — Jud
– Jud, Commented Nov 18, 2013 at 22:18

qdev76 · Accepted Answer · 2013-11-18 22:41:06Z

1

Seems to me like you want to be given directions rather than the answer. With that in mind, here's the thought process when I look at these problems:

In order to sort any list, you must go through the entire list at least once
- this implies looping of some sort (see loops) less general answer
How are you going to determine if it's even or odd?
- you'll probably need to perform some sort of math operation (see arithmetic operators) less general answer
What are you going to do with the number after you figure this out?
- are you going to put the results into new lists?
- are you going to modify the current list?
- other possibilities

My Full Procedure

edited Nov 18, 2013 at 22:41

answered Nov 18, 2013 at 22:28

qdev76

1491 silver badge9 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

DeMarco · Accepted Answer · 2013-11-19 10:09:59Z

1

You just have to make a loop through the array and place the even numbers in the last position.

Something like:

for(i=0;i<length(List);i++)
   if isEven(List[i]){
      tempvar=List[i];
      for(j=i;j<length(List)-1;j++) List[j]=List[j+1];
      List[j+1]=tempvar;
    }

edited Nov 19, 2013 at 10:09

answered Nov 18, 2013 at 22:33

DeMarco

6091 gold badge9 silver badges26 bronze badges

Comments

JoeC · Accepted Answer · 2013-11-18 22:30:25Z

0

keeping track of 2 indices, top and bottom

so you will have top = 0 and bottom = Size - 1 at the beginning

loop through the list to set the bottom index (Just to make sure the bottom index is pointing at the most bottom odd number)

loop through the list again with top = 0

if List[top]%2 != 0 // if its an odd number
    swap it with List[bottom]
    decrement bottom by 1
increment top by 1

until Size > top or top == bottom

Note: you will need to create your own list since the parameters are all constants so you can't modify the list that is passed to the function

answered Nov 18, 2013 at 22:30

JoeC

1,86014 silver badges12 bronze badges

Collectives™ on Stack Overflow

Manipulating an Array

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related