When using the bubble sort method to sort my array from smallest to largest its outputting an unexpected value of: -858993460.
Within the debugger i'm being prompted with "Stack around variable 'numb was corrupted'.
I'm currently using Visual studios to run the code.
I have also ran the same code within a new project with no results.
#include <iostream>
int main()
{
int length = 6;
int temp = 0;
int end = 6;
int numb[] = { 6, 5, 4, 3, 2, 1 };
for (int counter = length - 1; counter > 0; counter--)
{
for (int i = 0; i < end; i++)
{
if (numb[i] > numb[i + 1])
{
temp = numb[i + 1];
numb[i + 1] = numb[i];
numb[i] = temp;
}
}
for (int i = 0; i <= 5; i++)
{
std::cout << numb[i] << " ";
}
std::cout << "\n";
end--;
}
system("pause");
}
In you inner for loop where int i = 0; i < end; i++, you need to set the condition to be i < end - 1. This is because you are already going to be at the end of the array with i + 1 when swapping the indexes around.
Related
Normally I would use other methods to fix this program but I am not allowed to use advanced techniques for this project, and so what I have is more or less as far as I'm allowed to go.
So my program is meant to take in an array with 10 numbers and then output how many of each value is in the array. For example, {1, 1, 1, 1, 1, 2, 2, 2, 2, 2} is meant to return
5 1
5 2
However, it returns
6 1
4 2
I've made sure that the finalData and Data arrays are holding the proper values.
cout << count(data, data + MAX_VALUE, finalData[i+1]) << " " << data[i] << "\n";
seems to be outputting the wrong value.
for some reason. I believe the error is in my last function, getResults, more specifically the last for loop. Here is that function.
void getResults(int finalData[], int data[])
{
int temp[MAX_VALUE];
int j = 0;
for (int i = 0; i < MAX_VALUE - 1; i++)
if (finalData[i] != finalData[i + 1])
temp[j++] = finalData[i];
temp[j++] = finalData[MAX_VALUE - 1];
for (int i = 0; i < j; i++)
{
finalData[i] = temp[i];
}
for (int i = 0; i < j; i++)
{
cout << count(data, data + MAX_VALUE, finalData[i+1]) << " " << data[i] << "\n";
}
}
This is my complete code.
#include<iostream>
#include<iomanip>
#include<string>
#include<cmath>
#include <algorithm>
using namespace std;
void printHeader();
int getData(string);
void getResults(int finalData[], int data[]);
const int MAX_VALUE = 10;
int main(void)
{
int countValue = 0;
int freq = 0;
printHeader();
int data[MAX_VALUE] = {};
int frequency[MAX_VALUE] = {};
for (int i = 0; i < MAX_VALUE; i++)
{
cout << "Please enter data position " << i + 1 << "\n";
data[i] = getData("\nPlease enter a valid integer.\n");
}
sort(data, data + MAX_VALUE);
int values[MAX_VALUE] = {};
int secondData[MAX_VALUE] = {};
for (int i = 0; i < MAX_VALUE; i++)
{
secondData[i] = data[i];
}
getResults(data, secondData);
return 0;
}
void printHeader()
{
}
int getData(string error)
{
int userInput = 0;
do
{
cin >> userInput;
if (cin.fail())
{
cout << error;
}
} while (cin.fail());
return userInput;
}
void getResults(int finalData[], int data[])
{
int temp[MAX_VALUE];
int j = 0;
for (int i = 0; i < MAX_VALUE - 1; i++)
if (finalData[i] != finalData[i + 1])
temp[j++] = finalData[i];
temp[j++] = finalData[MAX_VALUE - 1];
for (int i = 0; i < j; i++)
{
finalData[i] = temp[i];
}
for (int i = 0; i < j; i++)
{
cout << count(data, data + MAX_VALUE, finalData[i+1]) << " " << data[i] << "\n";
}
}
Got the right answer. Made the changes I listed at the top as well as the following change to the count function.
cout << count(data, data + MAX_VALUE, finalData[i]) << " " << finalData[i] << "\n";
You have done a simple error. When you call getResults you pass the same array(pointer) to 2 different parameters. Now when you update finalData the unwanted side effect update also data(they are the same pointer(with different name). So when you call count will not return the expected result.
To solve this problem you can do a copy of the input array and give it as second parameter of getResults(...) function.
I'm trying to make my program sort this array of numbers from least to greatest but the output is coming out otherwise. In other words, I'm trying to not use a[4] because that's what this algorithm is doing but I can't figure out how. Thanks for reading.
Output:
9 12 3 14
#include <iostream>
using namespace std;
int main() {
int a[4] = {12, 9, 14, 3};
int temp;
for(int i = 0; i < 4; i++) {
if(a[i] > a[i + 1]) {
temp = a[i];
a[i] = a[i + 1];
a[i + 1] = temp;
}
cout << a[i] << " ";
}
return 0;
}
You have three errors:
Error 1: An out-of-bounds access during the loop.
This:
for(int i = 0; i < 4; i++)
should be
for(int i = 0; i < 3; i++)
The reason being is that if you use the first (wrong) version, you have a buffer overrun:
if(a[i] > a[i + 1]) // if i == 3, a[3+1] == a[4] == out-of-bounds
Error 2: Writing the output while sorting.
You're doing this:
cout << a[i] << " ";
in the middle of the sort. It makes no sense to print out the values of the array if the sort has not been completed.
This should be placed outside the sorting code (once the sorting has completed):
for ( int i = 0; i < 4; ++i)
cout << a[i] << " ";
Error 3: Incorrect implementation of bubble sort.
A bubble sort works by making multiple passes through the data until it is detected that the data is sorted. Your code only makes one pass through the data and then exits.
What you need to do is have a while or similar loop that has within it, the for loop. The while loop only gets executed if the data requires at least one more pass through the data. You will know when the data is sorted if the if condition in the for loop never executes (meaning no swaps occurred, thus the data is sorted).
Here is an example:
int temp;
bool is_sorted = false;
while ( !is_sorted ) // execute while data is not sorted
{
isSorted = true; // assume data is sorted
for(int i = 0; i < 3; i++)
{
if(a[i] > a[i + 1])
{
//.. swap the items
//...
isSorted = false; // swap made, so data was not sorted
}
}
}
There is already a header file called "algorithm" with which you can do that:
#include <iostream>
#include <algorithm>
using namespace std;
typedef pair<char, int> new_pair;
struct sorting{
bool operator() (int i, int j){return i < j;}
}test_sort;
int main(void){
int test[4] = {5, 2, 1, 10};
sort(test, test + 3, test_sort);
for(int i = 0; i <= 3; i++){
cout <<test[i] << endl;
}
return 0;
}
I wish I helped you.
Currently studying software engineering at college (first year) and made a program where the user enters how many entries there will be and then they input the times for each entry and it is sorted in descending order.
The problem I am having is when I enter a large number for the first input it doesn't sort correctly but the rest do. It would be great if someone could help me out with this and sorry for the noob question:P
The entire code:
#include "stdafx.h"
#include <iostream>
using namespace std;
int TotalSize = 0;
void getSpeed(int *CalculationTime, int NoOfCalculations)
{
for (int i = 0; i < NoOfCalculations; i++)
{
cout << "Please enter the speed of calculation " << i + 1 << "(Ms): "; cin >> CalculationTime[i];
}
}
void sort_speeds(int *CalculationTime, int NoOfCalculations)
{
// Sorting speeds in decending order
bool swapped = true;
int i, j = 0;
int temp;
while (swapped)
{
swapped = false;
j++;
for (i = 1; i < NoOfCalculations - j; i++)
{
if (CalculationTime[i] > CalculationTime[i + 1])
{
temp = CalculationTime[i];
CalculationTime[i] = CalculationTime[i + 1];
CalculationTime[i + 1] = temp;
swapped = true;
}
}
}
// Output times decending order
for (int i = 0; i < NoOfCalculations; i++)
{
cout << CalculationTime[i] << "\n";
}
}
int main()
{
// Declaring & Initializing variables
int NoOfCalculations = 0;
int *CalculationTime = new int[NoOfCalculations];
// Getting user input
cout << "How many calculations are there? "; cin >> NoOfCalculations;
getSpeed(CalculationTime, NoOfCalculations);
// Sorting and displaying times
sort_speeds(CalculationTime, NoOfCalculations);
system("pause");
return 0;
}
You've never compare first element of your array with anything - for (i = 1; i < NoOfCalculations - j; i++) should be for (i = 0; i < NoOfCalculations - j; i++)
The issue is for (i = 1; i < NoOfCalculations - j; i++) You are starting at position 1, start at position 0 and it fixes the problem. for (i = 0; i < NoOfCalculations - j; i++)
// Declaring & Initializing variables
int NoOfCalculations = 0;
int *CalculationTime = new int[NoOfCalculations];
// Getting user input
cout << "How many calculations are there? "; cin >> NoOfCalculations;
Bzzzt. You allocate a zero-element array, and then don't reallocate it. I bet if you entered a large enough number for your number of calculations, your program would crash.
Really, you want to be using std::vector, an extremely useful datastructure, the use of which is a bit outside of the scope of this answer. Basically, you can do stuff like this:
std::vector<int> getSpeeds(int NoOfCalculations)
{
std::vector<int> speeds;
for (int i = 0; i < NoOfCalculations; i++)
{
int speed;
std::cout << "Please enter the speed of calculation " << i + 1 << "(Ms): ";
std::cin >> speed;
speeds.push_back(speed);
}
return speeds;
}
You can use the returned vector almost exactly as if it were an array:
std::vector<int> speeds = getSpeeds(10);;
if (CalculationTime[3] > CalculationTime[4])
// do something
Often, in a C++ application, the explicit use of pointers is a sign that you're not using the standard library, and as a result making life much, much harder for yourself.
Oh, and also:
for (i = 1; i < NoOfCalculations - j; i++)
You never look at NoOfCalculations[0] or NoOfCalculations[i - 1], so you never touch the first element.
while (swapped)
{
swapped = false;
j++;
for (i = 0; i < NoOfCalculations - j; i++) //try and start i from 0. I think you are missing the first element to check
{
if (CalculationTime[i] > CalculationTime[i + 1])
{
temp = CalculationTime[i];
CalculationTime[i] = CalculationTime[i + 1];
CalculationTime[i + 1] = temp;
swapped = true;
}
}
}
So I'm creating a lottery ticket with random values and then sorting it. I'm not worried about the sorting technique since the teacher isn't looking for classes etc. on this assignment and it works, however, my ticket values that I produce - despite using srand (time(0)) and then later the rand() % 40 + 1 - which I think should make my randoms between 1-40... but mainTicket[0] always equals 0. Any ideas? Sorry about the formatting, made me add extra spaces and mess up my indention.
#include <iostream>
#include <cstdlib>
#include <time.h>
using namespace std;
void mainLotto (int main[]);
void lottoSort (int ticketArr[]);
int main()
{
int mainTicket[5];
srand (time(0));
mainLotto(mainTicket);
do
{
lottoSort(mainTicket);
} while (mainTicket[0] > mainTicket[1] || mainTicket[1] > mainTicket[2] || mainTicket[2] > mainTicket[3] || mainTicket[3] > mainTicket[4] || mainTicket[4] > mainTicket[5]);
for (int i = 0; i < 5; i++)
{
cout << mainTicket[i] << "\n\n";
}
return 0;
}
///
/// <> Creates the actual lottery ticket
///
void mainLotto (int main[])
{
// Creating the ticket
for (int i = 0; i < 5; i++)
{
main[i] = rand() % 40 + 1;
}
}
///
/// <> Sorts the actual lottery ticket
///
void lottoSort (int ticketArr[])
{
// Sorting the ticket
for (int j = 0; j < 5; j++)
{
if (ticketArr[j] > ticketArr[j+1])
{
int temp;
temp = ticketArr[j+1];
ticketArr[j+1] = ticketArr[j];
ticketArr[j] = temp;
}
}
}
I see two problems with your arrays being accessed out of bounds:
Here:
int main()
{
int mainTicket[5];
srand(time(0));
mainLotto(mainTicket);
do
{
lottoSort(mainTicket);
}
while(mainTicket[0] > mainTicket[1] || mainTicket[1] > mainTicket[2]
|| mainTicket[2] > mainTicket[3] || mainTicket[3] > mainTicket[4]);
// || mainTicket[4] > mainTicket[5]); // OUT OF BOUNDS!!!
for(int i = 0; i < 5; i++)
{
cout << mainTicket[i] << "\n\n";
}
return 0;
}
And here:
void lottoSort(int ticketArr[])
{
// Sorting the ticket
for(int j = 0; j < 4; j++) // j < 4 NOT 5!!! <== WAS OUT OF BOUNDS
{
if(ticketArr[j] > ticketArr[j + 1])
{
int temp;
temp = ticketArr[j + 1];
ticketArr[j + 1] = ticketArr[j];
ticketArr[j] = temp;
}
}
}
Likely the sort routine was dragging in a zero from out side the array bounds.
I just printed the item you claim to be always zero, after the mainLotto() and it yielded 30.
I suspect the problem lies where you tell us not to look. :)
In the sorting function you do:
for (int j = 0; j < 5; j++) {
if (ticketArr[j] > ticketArr[j + 1]) {
The array is of size 5. Your j will take eventually a value equal to 4.
Then you do ticketArr[j + 1], which is actually an out of bound access.
The fix is to go until 4 in your loop, not 5.
As Galik said, mainTicket[4] > mainTicket[5] is also an out of bounds access and after reading my answer, you should be able to understand why. :)
I've written out this particular code in C++ to try and find out all the multiples of the integers 3 & 5 below 1000 by using a while loop and then storing it in integer arrays. I also want to print each of those multiples out. But every time I debug this program, it endlessly prints out '0'. I just don't understand. Can someone please explain how to correct this code and why that unusual output occurs?
#include <iostream>
using namespace std;
int main()
{
const int three_limit = 334;
const int five_limit = 200;
int threeArray[three_limit] = {0};
int fiveArray[five_limit] = {0};
int i = 1, j = 1;
while (i < three_limit)
{
int multiples = 3*i;
multiples = threeArray[i - 1];
cout << threeArray[i - 1] << endl;
i++;
}
while (j < five_limit)
{
int multiples = 5*i;
multiples = fiveArray[j - 1];
cout << fiveArray[j - 1] << endl;
j++;
}
char response;
cin >> response;
return 0;
}
Your output will have duplicates when the number contains multiples of 3 and 5, e.g. 15, 30.
Some of the suggestions use multiplication or mod (%) which are quite slow, but there's a much faster solution using a binary array that will also help you avoid the duplication problem. Something like:
int main() {
bool nums[1001];
for(int i = 1; i < 1001; ++i)
nums[i] = 0;
for(int i = 3; i < 1001; i += 3)
nums[i] = 1;
for(int i = 5; i < 1001; i += 5)
nums[i] = 1;
for(int i = 1; i < 1001; ++i)
if(nums[i])
cout << i << endl;
}
It should be
threeArray[i - 1] = multiples;
instead of
multiples = threeArray[i - 1];
See the following code, to generate multiples of 5
#include<stdio.h>
int main(){
int max=1000;
int i=1,result=0;
while(result!=max && i!=200)
{
result=5*i; // change the 5 by 3 for multiples of 3
printf("\n %d",result);
i++;
}
}
I guess this
multiples = threeArray[i - 1];
should really be
threeArray[i - 1] = multiples;
Try debugging it again and watch multiples while executing this line.
multiples = threeArray[i - 1];
You're overwriting the local int with the (empty) contents of the array - you have your assignment the wrong way around.
You never modify the values in your array. It should be something like this:
while (i < three_limit)
{
int multiples = 3*i;
threeArray[i-1] = multiples;
cout << threeArray[i - 1] << endl;
i++;
}