Need help with reversing array

[Jose94ji]

I need to take the array that was generated and put into a file and reverse it. How can i do that? This is what i have so far. How can i make a function to do that?

  #include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

void populate();
void display();
void writeFile(ofstream& ,int[],int);

int main()
{
int choice;
cout << "Please Enter (1) if you wish to create a new set of randomly generated numbers \n";
 cout	<<  "Enter (2) if you wish to display the numbers that were generated \n"; 
 cout << "Enter (3) if you wish to see the randomly generated numbers in reverse order/n";
cin >> choice;
if(choice == 1)
{
      populate();
}
else
	  display(); 
    return 0;
}

void populate()

{int values[]={5, 10, 15, 20, 25, 30, 35, 95, 100};
int elements,seed,i;
int *array;
char filename[30];
ofstream out;
cout<<"Enter number of elements: ";
cin>>elements;
cout<<"Enter random number generator seed: ";
cin>>seed;
srand(seed);
array=new int[elements];
for(i=0;i<elements;i++)
    array[i]=values[rand()%7];
cout<<"Enter file name: ";
cin>>filename;
out.open(filename);
writeFile(out,array,elements);
cout<<"Operation successfully completed\n ";
 }

void display()
{
	char filename[50];
	ifstream my;

	cin.getline(filename, 50);
	cin >> filename;
	my.open(filename);
	if(!my.is_open()){
		exit(EXIT_FAILURE);
	}
		while(my.good())
		{
			int num;
			my >> num;
			cout << num << " ";
		}
		
}

void writeFile(ofstream& out ,int a[],int m)
{int i;
for(i=0;i<m;i++)
    out<<a[i]<<endl;
}

[AlitCandle]

Use this to generate each number to store in the array/vector:
http://www.cplusplus.com/reference/cstdlib/srand/

Writing to the file is simple enough:

#include <iostream>
#include <string>
#include <fstream>


using namespace std;

int main()
{
    int poot[5]{0, 1, 2, 3, 4};
	ofstream iambored("hello.txt");
	for(int i : poot)
    {
        iambored<<poot[i];
    }
    iambored.close();

	return 0;
}

Reading from a file is just as easy.

Reversing the array of ints. This depends on whether you want to reverse the actual number or the characters of the int. I will assume you want to reverse the characters of the int.

After you convert the int to a string:
http://stackoverflow.com/questions/5590381/easiest-way-to-convert-int-to-string-in-c

reverse it:
http://www.cplusplus.com/forum/beginner/11633/

then convert it back:
http://www.cplusplus.com/forum/general/13135/

[AlitCandle]

Also keep in mind you should probably switch to vectors and std::arrays. Also:
int poot[5]{0, 1, 2, 3, 4};

and

for(int i : poot)

are C++11 features which your compiler might not support

[vlad from moscow]

You should keep the number of elements and then read the file in dynamically allocated array and reverse it.

[giblit]

You can also even use this really handy library called algorithm if your teacher allows it. Then try this.

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#include <iostream> #include <algorithm> #include <vector> #include <cstdlib> #include <ctime> int unique_number( void ) { return( rand() % 100 ); } template <typename T> void output( const std::vector<T> &vec ) { for( const auto &it : vec ) { std::cout << it << " " << std::flush; } std::cout << std::endl; } int main() { srand( (unsigned) time( NULL ) ); const auto size( 9 ); std::vector<int> vec( size ); std::generate_n( vec.begin() , size , unique_number ); output( vec ); std::reverse( vec.begin() , vec.end() ); output( vec ); }

33 37 49 85 28 85 84 27 12 12 27 84 85 28 85 49 37 33 Process returned 0 (0x0) execution time : 0.244 s Press any key to continue.