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I don't understand why my code isn't working. The commented out code would remove the wrong characters and not remove any spaces, but the current delete_repeats function is giving me an error of: `line 49: expected initializer before numeric constant.
Can anyone help me?`
#include <iostream>
#include <string>
#include <cstring>
using namespace std;
void fill_array(char a[], int size, int& number_used);
void delete_repeats(char a[], int& number_used);
void sentences_output(char a[], int& number_used);
int main()
{
char sentences[100];
int used=0;
fill_array(sentences, 100, used);
delete_repeats(sentences, used);
sentences_output(sentences, used);
return 0;
}
void fill_array(char a[], int size, int& number_used)
{
char c;
int index = 0;
cout<<"Enter your sentence or sentences and press enter. \n"
<< "The max number of characters is 100.\n";
cin.get(c);
while((c != '\n')&&(index < size))
{
a[index]=c;
cin.get(c);
index++;
}
number_used = index;
cout<<"Your original array size was "<<number_used<<endl;
return;
}
void delete_repeats(char a[], int& number_used)
48{
int counter = number_used;
for (int i = 0; i < number_used; i++)
{
for (int j = i+1; j < number_used; j++)
{
if (a[i] == a[j])
{
for (int k = j; k < number_used - 1; k++)
{
a[k]= a[k + 1];
}
// } wrong place; j-- and size-- only if a duplicate
j--;
number_used--;
} // moved brace here
cout << "size = " << number_used;
cout << endl;
}
}
return;
}
/*
void delete_repeats(char a[], int& number_used)
{
int location = 0;
int target = 0;
int change;
for(location = 0; location < number_used; location++)
{
for(target = 0; target<number_used; target++)
{
change = target;
if(a[location] == a[target])
{
a[target] = a[change+(target - location)];
}
}
}
return;
}
*/
void sentences_output(char a[], int& number_used)
{
cout<<"The new sentence is \n";
for(int i = 0; i < number_used; i++)
{
cout<<a[i]<<endl;
}
cout<<"The size of the new array is \n";
cout<<number_used<<endl;
return;
}
The commented out delete_repeats was the second one I came up with and the first delete_repeats was from an example I found, but neither is working.
Thanks everyone! Here is my corrected code:
#include <iostream>
#include <string>
#include <cstring>
using namespace std;
void fill_array(char a[], int size, int& number_used);
void delete_repeats(char a[], int& number_used);
void sentences_output(char a[], int& number_used);
int main()
{
char sentences[100];
int used=0;
fill_array(sentences, 100, used);
delete_repeats(sentences, used);
sentences_output(sentences, used);
return 0;
}
void fill_array(char a[], int size, int& number_used)
{
char c;
int index = 0;
cout<<"Enter your sentence or sentences and press enter. \n"
<< "The max number of characters is 100.\n";
cin.get(c);
while((c != '\n')&&(index < size))
{
a[index]=c;
cin.get(c);
index++;
}
number_used = index;
cout<<"Your original array size was "<<number_used<<endl;
return;
}
void delete_repeats(char a[], int& number_used)
{
int counter = number_used;
for (int i = 0; i < number_used; i++)
{
for (int j = i+1; j < number_used; j++)
{
if (a[i] == a[j])
{
for (int k = j; k < number_used - 1; k++)
{
a[k]= a[k + 1];
}
j--;
number_used--;
}
}
}
return;
}
void sentences_output(char a[], int& number_used)
{
cout<<"The new sentence is \n";
for(int i = 0; i < number_used; i++)
{
cout<<a[i]<<" ";
}
cout<<"\n";
cout<<"The size of the new array is \n";
cout<<number_used<<endl;
return;
}
I removed the commented out delete_repeats function and edited the new one as well as changed the output function.
Did you include the line numbers in your actual code!? That would give the error you quote.
Related
I'm taking a C++ class and we've gotten to pointers. The assignment we've been given is to basically bubble sort an array that was read from a text file by passing pointers as parameters for various functions. I think I have a decent setup that outputs what I'm looking for, but for specific actions, I'm getting a zero as an element when there isn't one written to the array.
#include <iostream>
#include <fstream>
using namespace std;
int capacity;
int count;
int readData(int *&arr);
void swap(int *xp, int *yp);
void bsort(int *arr, int last);
void writeToConsole(int *arr, int last);
void bubble_sort(int *arr, int last, int(*ptr)(int, int));
int ascending(int a, int b);
int descending(int a, int b);
int main() {
int *whatever = NULL;
count = readData(whatever);
cout << "Raw array data:" << endl;
writeToConsole(whatever, capacity);
cout << "After simple bubble sort:" << endl;
bubble_sort(whatever, capacity, ascending);
writeToConsole(whatever, capacity);
cout << "Now descending:" << endl;
bubble_sort(whatever, capacity, descending);
writeToConsole(whatever, capacity);
return 0;
}
int readData(int *&arr) {
ifstream inputFile;
inputFile.open("data.txt");
if (!inputFile) {
cout << "Error!";
}
inputFile >> capacity;
arr = new int[capacity];
for(int i = 0; i < capacity; i++){
inputFile >> arr[i];
}
inputFile.close();
return capacity;
}
void swap(int *xp, int *yp) {
int temp = *xp;
*xp = *yp;
*yp = temp;
}
void bsort(int *arr, int last) {
int i, j;
bool swapped;
for (i = 0; i < last + 1; i++)
{
swapped = false;
for (j = 0; j < last-i; j++)
{
if (arr[j] > arr[j+1])
{
swap(arr[j], arr[j+1]);
swapped = true;
}
}
// IF no two elements were swapped by inner loop, then break
if (swapped == false)
break;
}
}
void writeToConsole(int *arr, int last) {
cout << "[ ";
for(int i = 0; i < last; i++){
cout << arr[i] << " ";
}
cout << "]" << endl;
}
void bubble_sort(int *arr, int last, int(*ptr)(int, int)){
int i, j;
bool swapped;
for (i = 0; i < last; i++)
{
swapped = false;
for (j = 0; j < last-i; j++)
{
//Use the function pointer to determine which logic to use
if (ptr(arr[j] , arr[j+1]))
{
swap(arr[j], arr[j+1]);
swapped = true;
}
}
// IF no two elements were swapped by inner loop, then break
if (swapped == false)
break;
}
}
int ascending(int a, int b){
return a > b;
}
int descending(int a, int b){
return a < b;
}
My output looks like this:
Raw array data:
[ 8 4 7 2 9 5 6 1 3 ]
After simple bubble sort:
[ 0 1 2 3 4 5 6 7 8 ]
Now descending:
[ 9 8 7 6 5 4 3 2 1 ]
Any ideas as to why my second sort is throwing in a zero? Thank you!
you have to do this change is in bubble_sort function
for (j = 1; j < last - i; j++)
{
//Use the function pointer to determine which logic to use
if (ptr(arr[j-1], arr[j]))
{
swap(arr[j-1], arr[j]);
swapped = true;
}
}
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Closed 6 years ago.
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I am new to programming so forgive me if question sounds trivial.Your any suggestion will be a great help in my learning.
I am writing up a Selection_Sorting program on the array of size 10. I am able to compile the program but after giving the input its reflecting this
message:
The sorted array as follows:
Abort trap: 6
My question is where to look in the program to troubleshoot the issue and what are the reasons this issue occurs ?
For reference I am attaching my code.
# include <iostream>
void fill_array(int sample_array[10], int size);
void sort(int sample_array[10], int size);
void swap(int &a1, int &a2);
int index_of_smallest(int array[10], int start_index, int size);
int main()
{
using namespace std;
int array[10];
fill_array(array, 10);
sort(array, 10);
cout << " The sorted array as follows : \n";
for (int i = 0; i < 10; i++)
{
cout << array[i] << " ";
}
return 0;
}
void fill_array(int sample_array[10], int size)
{
using namespace std;
for (int index = 0; index< 10; index++)
{
cin >> sample_array[index];
}
}
void swap(int &a1, int &a2)
{
int temp;
temp = a1;
a1 = a2;
a2 = temp;
}
int index_of_smallest(int array[10], int start_index, int size)
{
int min = array[start_index];
int min_index = start_index;
for (int i = start_index + 1; i< size - 1; i++)
{
if (array[i]< min)
{
min = array[i];
min_index = i;
}
}
return min_index;
}
void sort(int sample_array[10], int size)
{
int next_min_index;
int j;
for (j = 0; j < size; j++)
{
next_min_index = index_of_smallest(sample_array, j, 10);
}
swap(sample_array[j], sample_array[next_min_index]);
}
I decided to decipher the one function that would be most likely at fault. I've re-formatted it here to be readable:
void sort( int sample_array[10], int size )
{
int next_min_index;
int j;
for( j = 0; j < size; j++ )
{
next_min_index = index_of_smallest( sample_array, j, 10 );
}
swap( sample_array[j], sample_array[next_min_index] );
}
And now, hopefully you can see the problem.
The swap is not happening inside the loop. You moved the definition for j out of the loop scope (presumably to fix compile errors you didn't understand, which would have pointed you to the problem).
The swap is happening when j == 10. That is outside your array bounds and your program baulks. You should fix the error if you change the function to this:
void sort( int sample_array[10], int size )
{
for( int j = 0; j < size; j++ )
{
int next_min_index = index_of_smallest( sample_array, j, 10 );
swap( sample_array[j], sample_array[next_min_index] );
}
}
This might not be the only problem, but I'm not going to decipher the rest of your code. Hopefully this fix plus some strong encouragement to use human-readable code layout will help you along your way.
The following code is not working for heap sort. It looks ok to me. Can someone help me please? I have followed the pseudo code from CLRS, the sorted numbers are not being updated after the algorithm is traversed.
#include <iostream>
using namespace std;
void max_heapify(int *b, int i,int he_size)
{
int l,r,largest;
l=2*i;
r=(2*i+1);
if (l<=he_size && b[l]>b[i])
largest=l;
else largest=i;
if (r<=he_size && b[r]> b[largest])
largest=r;
if (largest!=i)
{
swap(b[i],b[largest]);
max_heapify(b,largest,he_size);
}
}
void build_max_heap(int *c,int h_size,int strlength)
{
for (int q=(strlength)/2;q==1;--q)
{
max_heapify(c,q,h_size);
}
}
void swap(int a, int b)
{
int c=b;
b=a;
a=c;
}
int main()
{
int length;
int heap_size;
cout<<"Enter the number of numbers to be sorted by heap sort"<<endl;
cin>>length;
int* a=NULL;
a=new int[length-1];
int temp;
cout<<"Enter the numbers"<<endl;
for(int i=0;i<length;i++)
{
cin>>temp;
*(a+i)=temp;
}
cout<<"The given numbers are:"<<endl;
for(int j=0;j<length;j++)
cout<<*(a+j)<<" "<<endl;
heap_size= length;
build_max_heap(a,heap_size,length);
for (int l=length;l==2;--l)
{
swap(a[1],a[length]);
heap_size=heap_size-1;
max_heapify(a,1,heap_size);
}
cout<<"The sorted numbers are:"<<endl;
for(int j=0;j<length;j++)
cout<<*(a+j)<<" "<<endl;
system("pause");
return 0;
}
The number of mistakes in your code is enormous. Sorry to say it.
void swap(int a, int b)
{
int c=b;
b=a;
a=c;
}
does nothing - a and b should be passed by link, not by value:
void swap(int &a, int &b)
{
int c=b;
b=a;
a=c;
}
for (int q=(strlength)/2;q==1;--q) is wrong. You meant for (int q=(strlength)/2;q>1;--q). Your loop is running only when q==1.
a=new int[length-1]; The size of array should be length, not length-1. And even though swap(a[1],a[length]); is wrong, because a[length] is out of array.
Also there are some mistakes in algorithm. I tried to rewrite as less code as possible.
Right code is:
#include <iostream>
using namespace std;
void sift_down(int *a, int start, int end) {
int root = start;
while (root * 2 + 1 <= end) {
int child = root * 2 + 1;
int sw = root;
if (a[sw] < a[child])
sw = child;
if (child + 1 <= end and a[sw] < a[child + 1])
sw = child + 1;
if (sw == root)
return;
else
swap(a[root], a[sw]);
root = sw;
}
}
void max_heapify(int *b, int count) {
int start = (count - 2) / 2;
while (start >= 0) {
sift_down(b, start, count - 1);
--start;
}
}
void swap(int &a, int &b) {
int c = b;
b = a;
a = c;
}
int main() {
int length;
int heap_size;
cout << "Enter the number of numbers to be sorted by heap sort" << endl;
cin >> length;
int *a = new int[length];
cout << "Enter the numbers" << endl;
for (int i = 0; i < length; i++) {
cin >> a[i];
}
cout << "The given numbers are:" << endl;
for (int j = 0; j < length; j++)
cout << a[j] << " ";
cout << endl;
heap_size = length;
max_heapify(a, heap_size);
--heap_size;
while (heap_size) {
swap(a[heap_size], a[0]);
--heap_size;
sift_down(a, 0, heap_size);
}
cout << "The sorted numbers are:" << endl;
for (int j = 0; j < length; j++)
cout << a[j] << " ";
cout << endl;
//system("pause");
return 0;
}
I know the logic how to merge two arrays but the problem is how to code.
This was my code n it is giving correct ans but my sir told me that do it again,please tell me what I have to add in this code,
#include<iostream>
using namespace std;
int mergeArrays(int array1[],int size1,int array2[],int size2);
int main()
{
const int size1=8;
const int size=12;
int arrayA[size1]={10,25,37,49,50,51,55,60};
int arrayB[size]={2,5,26,27,29,32,40,45,70,80,90,95};
mergeArrays(arrayA,size1,arrayB,size);
}
int mergeArrays(int array1[],int size1,int array2[],int size2)
{
int size3=size1+size2;
int *array3=new int[size3];
int k=0;
for(int i=0;i<size1;i++)
{
array3[k]=array1[i];
cout<<" "<<array3[k];
}
int j=0;
for(int i=size1;i<size2;i++)
{
array3[k]=array2[j];
}
for(int i=size1;i<size2;i++)
{
for(int j=0;j<size2;j++)
{
array3[i]=array2[j];
cout<<" "<<array3[i];
}
cout<<endl;
delete[]array3;
return array3[k++];
}
}
I had searched this in many places but could not corrected my code
I had written this code but it is not giving correct ans.
#include<iostream>
using namespace std;
int merge(int *a,int *b,int aSize,int bSize);
int main()
{
const int aSize={8};
const int bSize={12};
int arrayA[aSize]={10,25,37,49,50,51,55,60};
int arrayB[bSize]={2,5,26,27,29,32,40,45,70,80,90,95};
merge(arrayA,arrayB,aSize,bSize);
return 0;
}
int merge(int *a,int *b,int aSize ,int bSize)
{
int cSize=aSize+bSize;
int *c=new int[cSize];
int j=0,k=0;
int i=0;
while(i<=aSize&&j<=bSize )
{
if(a[aSize ]<=b[bSize])
{
c[k]=a[aSize];
k++;
i++;
}
else
{
c[k]=b[bSize];
k++;
j++;
}
}
for(int i=0;i<k;i++)
{
cout<<c[i]<<endl;
}
delete[]c;
return c[k++];
}
your sir request you do Merging two arrays in ascending order. so i think you should return a new array, fill with array1 and array2's element, and the elements should be ascending order. here is a implement.(suppose your input arraies is already in ascending order.)
#include <iostream>
using namespace std;
int mergeArrays(int array1[],int size1,int array2[],int size2, int outArray[]);
int main()
{
const int size1=8;
const int size=12;
int arrayA[size1]={10,25,37,49,50,51,55,60};
int arrayB[size]={2,5,26,27,29,32,40,45,70,80,90,95};
int outArray[size1+size];
int len = mergeArrays(arrayA,size1,arrayB,size, outArray);
cout <<" "<< len;
for (int i = 0; i< size1+size; ++i){
cout <<" " << outArray[i];
}
}
int mergeArrays(int array1[], int size1, int array2[], int size2, int outArray[])
{
int i=0, j=0, k=0;
int retSize = size1+size2;
while (k<retSize){
if (i==size1){// only left array2, copy it
for (; j<size2; ++j){
outArray[k++] = array2[j];
}
}else if (j == size2) { // only left array1, copy it
for (; i<size1; ++i){
outArray[k++] = array1[i];
}
}
else if (array1[i] > array2[j]){ // copy the min value to outArray
outArray[k++] = array2[j++];
}else{
outArray[k++] = array1[i++];
}
}
return k;
}
now, let's look at your first code:
int mergeArrays(int array1[],int size1,int array2[],int size2)
{
int size3=size1+size2;
int *array3=new int[size3];
int k=0;
for(int i=0;i<size1;i++)
{
array3[k]=array1[i]; // k is not changed, so you just assign array1's each value to array3[0]
cout<<" "<<array3[k];
}
int j=0;
// what's the purpose of this loop?
// and in loop, you don't use i, you just repeat set array3[0] = array2[0]!!
for(int i=size1;i<size2;i++)
{
array3[k]=array2[j];
}
for(int i=size1;i<size2;i++) // if array2's length bigger than array1's, will enter this loop.
{
for(int j=0;j<size2;j++)
{
array3[i]=array2[j]; // this just repeat assign array2's each value to array3[i]!!
cout<<" "<<array3[i];
}
cout<<endl;
delete[]array3;
return array3[k++]; // you delete array3, but at here you access it!! this will crash!
// also, in this for i loop, you have return, so it will only execute once.
}
// reach function end and no return if not enter for loop.
}
I haven't looked at your second code. I think you still need to do more study.
I am trying to implement Quick Sort algorithm. Following code works for unique elements but it doesn't working for arrays having duplicate elements. Please tell me where I am doing wrong. Also when I change value of pivot to some other number other than 0 , program crashes. Here is the code:
#include <iostream>
#include <cstdlib>
using namespace std;
void swapme(int &a, int &b)
{
int temp = a;
a = b;
b = temp;
}
void quicksort(int *arr, int size)
{
// these two variables will take care of position of comparison
int lower = 0, upper = size - 1;
int pivot = 0; // assigns pivot
if (size <= 1)
return;
while (lower < upper)
{
while (arr[lower] < arr[pivot])
{
++lower;
}
}
while (arr[upper] > arr[pivot])
{
--upper;
}
if (upper > lower)
{
swapme(arr[upper], arr[lower]);
// upper--;
// lower++;
}
quicksort(arr, lower);
quicksort(&arr[lower + 1], size - 1 - lower);
}
int main()
{
int arr[30];
for(int j = 0; j < 30; j++)
{
arr[j] = 1 + rand() % 5000;
}
for(int j = 0; j < 30; j++)
{
cout << arr[j] << "\t";
}
cout << endl;
quicksort(arr, 30);
for(int j = 0; j < 30; j++)
{
cout << arr[j] << "\t";
}
cout << endl;
cin.get();
cin.get();
}
Update: I have finally managed to make it work. Here is the fixed version:
void swapme(int &a, int &b )
{
int temp = a;
a = b;
b = temp;
}
void quicksort(int *arr, int size)
{
if (size <= 1)
return;
// These two variables will take care of position of comparison.
int lower = 0;
int upper = size-1;
int pivot = arr[upper/2]; // assigns pivot
while (lower <= upper)
{
while (arr[lower] < pivot)
++lower;
while (arr[upper] > pivot)
--upper;
if (upper >= lower)
{
swapme(arr[upper],arr[lower]);
if(arr[upper] == arr[lower])
{
// Can either increment or decrement in case of duplicate entry
upper--; // lower++;
}
}
}
quicksort(arr, lower);
quicksort( &arr[lower+1], size-1-lower);
}
You are storing the index of your pivot element in the pivot variable, so swapping the elements can potentially change the choice of pivot element during the loop. Not a very good idea. I would suggest storing the actual value of the pivot element inside pivot instead.
Also, if this really isn't homework, why don't you simply use the standard library facilities?
#include <algorithm>
// ...
std::sort(arr + 0, arr + 30);
You will get heavily optimized and tested code that will outperform your handwritten Quicksort anytime.
Quick Sort that can implement any number of i/p integers. it also deal with duplicate keys
#include <conio.h>
#include <string>
using namespace std;
void InputArray(int*,int);
void QuickSort(int *,int,int);
int partition(int *,int,int);
void swap(int *,int,int);
void printArr(int *,int Siz=11);
void main(){
int siz;
cout<<"Enter Array length : "; cin>>siz;
int *a=new int[siz];
InputArray(a,siz);
QuickSort(a,0,siz-1);
int i=0,j=11;
printArr(a,siz);
system("pause");
}
void InputArray(int*a,int s){
for(int i=0; i<s; i++){
cout<<"ELement ["<<i<<"] = "; cin>>a[i];
}
}
void QuickSort(int *a,int start,int end){
if(start<end){
int pivot=partition(a,start,end);
QuickSort(a,start,pivot);
QuickSort(a,pivot+1,end);
}
}
int partition(int *a,int start,int end){
int currentPivotValue=a[start];
int i=start-1, j=end+1;
while(true){
i++;
while(i<j && a[i]<currentPivotValue){ i++; }
j--;
while(j>start && a[j]>currentPivotValue) {j--;}
if(i<j) swap(a,i,j);
else return j;
}
}
void swap(int *b,int i,int j){
int t=b[i];
b[i]=b[j];
b[j]=t;
}
void printArr(int *a,int Siz){
for(int i=0; i<Siz; i++) cout<<a[i]<<" ";
}