hey guys I need help for my read code seems not working properly here's the code. The problem is as shown in the picture, the compiler are supposed to display all 1 million int value but it seems that my write or the display code was wrong. It shows nothing like it's not even reading.
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
#include <vector>
#include <omp.h>
#include <ctime>
#include <cstdlib>
using namespace std;
int* CreateArray( int*);
void shellSortParallel( int*, int);
void shellSortSequential(int*, int);
void InsertSort( int*, int, int, int);
int main()
{
int array_size = 1000000;
int n=0;
int* arr=new int[array_size];
ifstream fin("OUTPUT1.txt");
if(! fin)
{
cout << "File could not be opened." << endl;
}
else
{
cout << "File Opened successfully!!!. Reading data from file into array" << endl;
int data;
while(fin>>data)
{
arr[n] = data;
n++;
}
cout << "Displaying Array..." << endl << endl;
for(int i = 0; i < array_size; i++)
{
cout << arr[i];
}
}
fin.close();
int length = 1000000;
double endTime = 0, startTime = 0, totalTime = 0;
double start, end;
cout << "Program is now sorting using shell sort" <<endl;
startTime = time(NULL);
start = omp_get_wtime();// Start performance timer 1 run
shellSortParallel(arr, length);//Run the algorithm
end = omp_get_wtime();// End performance timer 1 run
endTime = time(NULL);
totalTime = endTime - startTime;
cout << "This is the time it took to run. " << totalTime << endl;// time in seconds
int stupid = 0;
cin >> stupid;
cout << "Program has completed all tasks!!" << endl;
return 0;
}
void shellSortParallel(int array[], int length)
{
int h;
int j = 0;
int temp = 0;
int i = 0;
for(h =length/2; h > 0; h = h/2)
{
#pragma omp parallel for shared( array, length, h, i) default(none)
for( i = 0; i < h; i++)
{
//int ID = omp_get_thread_num();
InsertSort(array, i, length, h);
}
}
}
void InsertSort(int arr[], int i, int length, int half)
{
//cout << ID << " ";
int temp = 0;
int j = 0;
for (int f = half + i; f < length; f = f + half)
{
j = f;
while(j > i && arr[j-half] > arr[j])
{
temp = arr[j];
arr[j] = arr[j-half];
arr[j-half] = temp;
j = j -half;
}
}
}
and here is the short version of the file that I'm going to read. Its a random number between 1 to 1million per line
2377763
88764877846
281327
60
625
86
646127818
14551
2177645
32033
1826761
555173
3415445377
32430
1101
any help would be much appreciate, thank you before
By if(fin>>data) you are not just testing, but retrieving data from stream. I suggest use ifs.good() for testing. Overall, you can write such a code instead
std::ifstream fin ("OUTPUT1.txt", std::ifstream::in);
char c = fin.get();
while (fin.good())
{
std::cout << c;
c = fin.get();
}
arr[n-1] = '\0'; is not correct because it's not an array of character so don't mind.
to correct it:
int data;
while(fin>>data)
{
arr[n] = data;
n++;
}
cout << "Displaying Array..." << endl << endl;
for(int i = 0; i < array_size; i++)
{
cout << arr[i];
}
why allocating such huge array of integers? use vector is a good thing:
vector<int> vec;
ifstream fin("OUTPUT1.txt");
int data;
while(fin >> data)
{
vec.push_back(data);
}
cout << "Displaying Array..." << endl << endl;
for(int i = 0; i < vec.size(); i++)
cout << vec[i] << endl;
fin.close();
88764877846 out band of an integer which causes the loop stop reading so you have to either get values as strings then convert into __int64 or __int128
to read values as strings:
string sLine;
int nLines = 0;
ifstream fin("OUTPUT1.txt");
// first read to get number of lines
while(getline(fin, sLine))
nLines++;
//create an array of strings
string* pstrValues = new string[nLines];
// set the get pointer to the beginning of file because the previous read moved it
fin.clear();
fin.seekg(0, ios::beg);
int i = 0;
while(getline(fin, sLine))
{
pstrValues[i] = sLine;
i++;
}
cout << "Displaying Array..." << endl << endl;
for( i = 0; i < nLines; i++)
cout << pstrValues[i] << endl;
fin.close();
now you have an array of strings convert it to int values but you must convert to __int64 because as I said there are values bigger than size of int (4bytes)
I am new to C++. I am trying to solve a problem in the textbook: swap the first and last element in an array. But when I run the code I wrote, nothing happened and even the sentence "Please enter the numbers in the array: " does not show up. Anyone could give some help? Thanks.
#include <iostream>
using namespace std;
int swap(int values[], int size)
{
int temp = values[0];
values[0] = values[size-1];
values[size-1] = temp;
}
int main()
{
const int SIZE = 5;
int test[SIZE];
cout << "Please enter the numbers in the array: " << endl;
int input;
cin >> input;
for(int i=0; i<SIZE; i++)
{
test[i] = input;
}
swap(test, SIZE);
cout << test[SIZE] << endl;
return 0;
}
There were a few mistakes:
You should get the input inside the loop and then assign it to the test array.
When printing the swapped value, access the test array with SIZE-1 instead of SIZE, because array indexes run from 0 to SIZE-1, inclusive.
You declared swap() as returning int, but provided no return statement (this suggests that you haven't enabled enough warnings from your compiler).
#include <iostream>
using namespace std;
void swap(int values[], int size)
{
int temp = values[0];
values[0] = values[size-1];
values[size-1] = temp;
}
int main()
{
const int SIZE = 5;
int test[SIZE];
int input;
cout << "Please enter the numbers in the array: " << endl;
for(int i=0; i<SIZE; i++)
{
cin >> input;
test[i] = input;
}
swap(test, SIZE);
cout << test[SIZE-1] << endl;
return 0;
}
#include <iostream>
using namespace std;
//Here return type should be void as you are not returning value.
void swap(int values[], int size)
{
int temp = values[0];
values[0] = values[size-1];
values[size-1] = temp;
}
int main()
{
const int SIZE = 5;
int test[SIZE];
cout << "Please enter the numbers in the array: " << endl;
//USE LOOP TO TAKE INPUT ONE BY ONE IN AN ARRAY
for(int i = 0; i < SIZE; i++)
cin >> test[i];
swap(test, SIZE);
//USE LOOP TO DISPLAY ELEMENT ONE BY ONE
for(int i = 0; i < SIZE; i++)
cout << test[i] << endl;
return 0;
}
my question refers to dynamic arrays in C++. I'm new at the language so please spell things out for me where possible.
I was wondering how I could change the following code to accept floats?
#include <iostream> // include library
using namespace std;
int main() // main function
{
int length;
cout << "Please enter the length of the array: "; // ask user for array
cin >> length;
int *dArray;
dArray = new int[length];
for (int i = 0; i < length; i++)
{
dArray[i] = i;
}
for ( int i = 0; i < length; i++)
{
cout << dArray[i] << " ";
}
delete[] dArray;
return 0;
Here's a more safe and easy way to write that code:
#include <iostream>
#include <vector> // std::vector
using namespace std;
int main()
{
int length;
cout << "Please enter the length of the array: ";
cin >> length;
vector<int> dArray( length );
for( int i = 0; i < length; ++i )
{
dArray[i] = i;
}
for( int i = 0; i < length; ++i )
{
cout << dArray[i] << " ";
}
}
The basic floating point type in C++ is called double. E.g. the literal 3.14 is of type double. So you can use that instead of int for the array item type.
I have a program that sorted arrays how can i save in text file?
for example: the sorted arrays is: 1, 2, 3, 4, 5.
how can i save in text file named. Sorted elements".
I've tried many ways but the sorted array wouldn't save in text file.
I am a newbie so I find it difficult.
here is my code.
#include <iostream>
using namespace std;
int main() {
cout << "Enter number of element:";
int n; cin >> n;
int a[n];
for(int i=0;i<n;i++)
{
cout << "element number " << (i+1) << " : ";
cin >> a[i];
}
int e=1, d=3;
int i, j, k, m, digit, row, col;
int length = sizeof(a)/sizeof(int);
int bmat[length][10];
int c[10];
for(m=1;m<=d;m++)
{
for(i=0;i<10;i++)
{
c[i]=-1;
}
for(i=0;i<length;i++)
{
digit=(a[i]/e)%10;
c[digit]++;
row=c[digit];
col=digit;
bmat[row][col]=a[i];
}
k=-1;
for(i=0;i<10;i++)
{
if(c[i]!=-1)
{
for(j=0;j<=c[i];j++)
{
k++;
a[k]=bmat[j][i];
}
}
}
e=e*10;
}
cout << endl;
cout << "Sorted array:" << endl;
for(int i=0;i<n;i++)
{
cout << a[i] << " , ";
}
cout << endl;
system("pause");
return 0;
}
//Use this code
#include <iostream>
#include <vector>
#include <algorithm>
#include <fstream>
using namespace std;
int main()
{
int n = 0;
cout << "Enter number of element:";
cin >> n;
//Data Structure
std::vector<int> list;
//push back element in vector
for(register int i=0;i<n;++i)
list.push_back(rand()%10 + 1);
//do shuffling before sorting because rand() generates increasing order number
std::random_shuffle(list.begin(),list.end());
std::sort(list.begin(),list.end());
ofstream textfile;
textfile.open ("E:\\example.txt");
for(size_t i= 0;i<list.size();++i)
textfile << list[i] <<" ";
textfile.close();
}
If you can write the sorted array to std::cout, then you can write it to a file. In C++, the console is the same as a file.
Put this at the end of main:
cout << "Sorted array:" << endl;
print_array( std::cout, a, n ); // Show the results to the user.
std::ofstream save( "array.txt" ); // Open a new file (or overwrite).
print_array( save, a, n ); // Save the results for later.
system("pause");
return 0;
}
and put the printing code in a new function, which may be defined before main:
void print_array( std::ostream & s, int * a, int n ) {
for(int i=0;i<n;i++)
{
s << a[i] << " , ";
}
s << endl;
}
#include<iostream>
#include<fstream>
using namespace std;
int compare(int, int);
void sort(int[], const int);
int compare(int x, int y){
return(x > y);
}
void swap(int *x, int *y){
int temp;
temp = *x;
*x = *y;
*y = temp;
}
void display(int array[], int n){
for (int i = 0; i<n; i++) {
cout << array[i] << " ";
}
cout << endl;
}
void writeToFile(int array[], int n){
ofstream myfile;
myfile.open("example.txt");
for (int i = 0; i<n; i++) {
myfile << array[i];
if (i != n - 1){
myfile << ", ";
}
}
myfile.close();
}
void sort(int table[], const int n) {
for (int i = 0; i < n; i++){
for (int j = 0; j < n - 1; j++) {
if (compare(table[j], table[j + 1]))
swap(&table[j], &table[j + 1]);
}
}
}
int main(){
int quantity;
int* tab;
ofstream outfile;
cout << "Enter number of element: ";
cin >> quantity;
tab = new int[quantity];
cout << "Element:\n\n" << endl;
for (int i = 0; i < quantity; i++){
int x = i;
cout << "#" << ++x << ":";
cin >> tab[i];
}
sort(tab, quantity);
cout << "The Sorted Elements are: ";
display(tab, quantity);
writeToFile(tab, quantity);
cout << endl;
getchar();
getchar();
//system("pause");
return 0;
}
in short, add this block to your code:
ofstream myfile;
myfile.open("example.txt");
for (int i = 0; i<n; i++) {
myfile << array[i];
if (i != n - 1){
myfile << ", ";
}
}
myfile.close();
You can use C++ fstream class, since you want to output, you can use ofstream here. You should just replace some "cout" with ofstream instance:
At the beginning of the code state it:
ofstream ofs("./sorted_elem.txt", ofstream::out);
When want to output:
ofs << "Sorted array:" << endl;
for(int i=0;i<n;i++)
{
ofs << a[i] << " , ";
}
ofs << endl;
In C++ you really want to use std::vector or some other nice container for storing arrays of numbers. For writing an array to file you need to open the file and individually write each element to the file (all untested).
#include <fstream>
int main()
{
std::ofstream fp("output.txt");
int data[5]; // todo: fill
for (unsitned i = 0; i < 5; ++i)
{
fp << data[i] << ' ';
}
}
And to read again:
#include <fstream>
int main()
{
std::ifstream fp("output.txt");
// todo: Determine the size of the array or guess it (don't guess it!)
unsigned array_size = 5;
int data[array_size];
int n = 0;
while (fp.good() && n < array_size) fp >> data[n++];
}
But because we are using C++, we can use std::vector:
#include <fstream>
#include <vector>
int main()
{
std::vector<int> me(5); // todo: fill
std::ofstream fp("output.txt");
for (size_t i = 0; i < me.size(); ++i) fp << me[i] << ' ';
// C++11: for (int d : me) fp << d << ' ';
}
And,
#include <fstream>
#include <vector>
int main()
{
std::ifstream fp("output.txt");
std::vector<int> data;
double buf;
while (fp >> buf) data.push_back(buf); // no longer need to guess
}
I think, the copy option was not demonstrated here so far.
Please check this code. (Assuming your vector is ready to use, I've skipped it).
The example uses a C-array and a vector. Please use the later in your code whenever possible. But however, for copy-function both work:
#include <iostream>
#include <iterator>
#include <vector>
#include <algorithm>
#include <fstream>
int main () {
int a[10]={0,1,2,3,4,5,6,7,8,9};
std::vector<int> v; for (int i=0; i<10; ++i)v.push_back(i*10); //0, 10, 20,...
std::ofstream fs_a( "c:/temp/out_a.txt" );
//store space separated
std::copy ( a, a+sizeof(a)/sizeof(a[0]), std::ostream_iterator<int>( fs_a, " ") );
//store coma-separated, as one-liner
std::copy ( v.begin(), v.end() ), std::ostream_iterator<int>( std::ofstream( "c:/temp/out_v.txt" ), ",") );
return 0;
}
When I output the code on the second line of output there is a space added in that I cannot figure out how to remove. I have searched on this site and google for an answer. Sorry this is a simple fix. Would post a picture but dont have enough reputation.
#include<iostream>
#include<iomanip>
#include<fstream>
using namespace std;
// global constant variables
const int YEARS = 8;
const int MONTHS = 12;
const int SPACER =5;
// function prototypes
// function to read in values
void getData(double[][MONTHS], int[]);
// function to display values in table format
void printData(double[][MONTHS], int[]);
// function to print data to screen in table format using arrays
int main()
{
double rain [YEARS][MONTHS];
int years[YEARS];
/*cout << " ";*/
getData(rain, years);
printData(rain, years);
return 0;
}
// function definitions
void getData (double rainArray[][MONTHS], int yearArray[])
{
ifstream fin;
fin.open("rainfall.txt");
if (!fin)
{
cout << "Error opening file, shutting down now.\n" ;
exit(EXIT_FAILURE);
}
else
{
for( int i = 0; i < YEARS; i++)
{
fin >> yearArray[i];
for (int j = 0; j < MONTHS; j++)
{
cout << fixed << setprecision(1);
fin >> rainArray[i][j];
}
}
}
fin.close();
}
void printData (double rainArray[][MONTHS], int yearArray[])
{
for ( int i = 0; i < YEARS; i++){
cout << yearArray[i] << setw(SPACER);
for ( int j = 0; j < MONTHS; j ++)
{cout << rainArray[i][j] << setw(SPACER);
if (j == 11)
cout << endl;
}
}
}
The setw() calls (as with all stream manipulators) need to be before the item whose printing they're meant to affect.
cout << setw(SPACER) << yearArray[i];
You were placing them after the items, so they took effect on all lines except the first (giving the results described in the question).
You need to write setw() before the field it applies to, not after.
void printData (double rainArray[][MONTHS], int yearArray[])
{
cout << fixed << setprecision(1);
for ( int i = 0; i < YEARS; i++){
cout << setw(SPACER) << yearArray[i];
for ( int j = 0; j < MONTHS; j ++)
{cout << setw(SPACER) << rainArray[i][j];
}
count << endl;
}
}