C++ Lowest 2 Values in Array

ktulu123 · 27-08-2009 11:54AM #1

Hey, i'm trying to find the lowest 2 values in an array, I have to do this without adding additional data members. This is what I have so far:

#include<iostream>
using namespace std;
int main()
{

int marks[10] = {9,8,7,6,5,4,3,2,1};
int i;

for(i=0;i<10;i++)
{
if(marks < marks[0])
{
marks[0] = marks;
}
}

cout<<"The Lowest number is "<<marks[0]<<endl;

for(i=1;i<10;i++)
{
if(marks < marks[1])
{
marks[1] = marks;
}
}

cout<<"The second lowest number is "<<marks[1];
}

Cheers

Edit - Yeah forgot a question, when i run this it just returns two zeros as both of the lowest members, what am i doing wrong? I dont want to use any sorting algorithms as this is only a 4 mark question on the paper!

Sparks · 27-08-2009 11:58AM

Is there a question in there?
Oh, and you've got a design bug. What happens if the second-lowest-value element in the array is the first element of the array?

mark renton · 27-08-2009 11:59AM

check out your sorts - bubblesort/quicksort etc

there are many ways of doing this

Sparks · 27-08-2009 12:06PM

Sorting's a waste of time for that task though.

nVid · 27-08-2009 12:07PM

Its mostly about making your own algorithm,

But the second loop will miss the first element I[0].

Try an && with || statment, get creative.

Sparks · 27-08-2009 12:13PM

ktulu123 wrote: »

this is only a 4 mark question on the paper!

Why would it matter that it's only four marks if this is an old paper you're using for study?

mark renton · 27-08-2009 12:15PM

thanks sparks - my laziness is profound sometimes

mark renton · 27-08-2009 12:30PM

see attachment for tutorial

mods can pull this down if not permitted

ktulu123 · 27-08-2009 02:09PM

Sweet got it out by realizing that once I got the lowest value i had to ignore it in the second array!
Cheers for the help!

#include<iostream>
using namespace std;
int main()
{

int marks[10] = {9,8,7,6,5,4,3,2,1};
int i;

for(i=0;i<9;i++)
{
if(marks < marks[0])
{
marks[0] = marks;
}
}

cout<<"The Lowest number is "<<marks[0]<<endl;

for(i=1;i<8;i++)
{
if(marks < marks[1])
{
marks[1] = marks;
}
}

cout<<"The second lowest number is "<<marks[1];
}

Sparks · 27-08-2009 02:29PM

That's still broken code ktulu.
Change marks[] to this and try it:

int marks[10] = {1,0,2,3,4,5,6,7,8,9};

(and your marks[] definition creates an array with 10 spaces and 9 values - for bonus points, what happens when you access the tenth space in the array?)

and what happens with this array?
int marks[10] = {1,1,1,2,3,4,5,6,7,8};

mark renton · 27-08-2009 02:57PM

Sparks wrote: »

(and your marks[] definition creates an array with 10 spaces and 9 values - for bonus points, what happens when you access the tenth space in the array?)

returns memory location

BP Pleeeze

mark renton · 27-08-2009 03:05PM

Sparks wrote: »

and what happens with this array?
int marks[10] = {1,1,1,2,3,4,5,6,7,8};

stops in line of code

if(marks < marks[0])

another BP pleeze

do i still have it or what

Anima · 28-08-2009 03:54AM

This forum isn't generally a place for gloating mate. Just because you might know something someone else doesn't know, doesn't warrant you posting like that. Grow up.

Sparks · 28-08-2009 04:33AM

Especially after two wrong answers...

mark renton · 28-08-2009 09:37AM

:eek:

My God arent we all terribly serious in here

mark renton · 28-08-2009 09:46AM

Sparks wrote: »

Especially after two wrong answers...

Ok im a bit rusty and my tutor wuld not be pleased but I should get some marks for being in the general vicinity of teh correct answer - no?

mark renton · 28-08-2009 02:13PM

Can somebody throw me a bone here please people????

Cccmmmooonnn

Captain Furball · 28-08-2009 02:16PM

What part don't you not understand John?

mark renton · 28-08-2009 04:19PM

Captain Furball wrote: »

What part don't you not understand John?

Thanks anyway dude - was just giving others the opportunity to apologise for hurtin me feelins

dont know how these people sleep at night

Captain Furball · 28-08-2009 05:47PM

Lol I was under the impression you didn't know how to do something haha.
My apologies John.

boars.ie · 28-08-2009 09:16PM

What C++ specific is in this task? I mean, except "cout<<"?

#include <stdio.h>

int main(int argc, char** argv) {
 int array[11], size = 0, firsti = -1, secondi = -1, i;
 char c;

 for(i = 1; i < argc && size < sizeof(array)/sizeof(int); i++)
   if (sscanf(argv[i], " %d %c ", array + size, &c) == 1) size++;

 if (size > 0 && size < sizeof(array)/sizeof(int))
   for(firsti = 0, i = 1; i < size; i++) {
     if (array[firsti] > array[i]) {
       secondi = firsti;
       firsti = i;
     } else {
       if (array[firsti] < array[i] && (array[secondi] > array[i] || secondi < 0)) secondi = i;
     }
   }

 if (firsti >= 0) fprintf(stderr, "first lowest: array[%d]=%d\n", firsti, array[firsti]);
 if (secondi >= 0) fprintf(stderr, "second lowest: array[%d]=%d\n", secondi, array[secondi]);

 return 0;
}

Sparks · 28-08-2009 09:27PM

john47832 wrote: »

I should get some marks for being in the general vicinity of teh correct answer - no?

No.

C++ Lowest 2 Values in Array

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