How can save the return of a function to another array?

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I wrote a function which returns an array; so how can I save (copy) that returned array into another array. What is the best and fastest way?

C++

//function declaration
int func (int array[]);

// function defenition
int func (int array[]){
     ....
    return result[];
}

Posted 4-Aug-15 22:42pm

amin.j

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Philippe Mori 5-Aug-15 13:30pm

Write real C++ code using STL containers like std::vector. It does not make much sense to use C style array in 2015.

amin.j 5-Aug-15 13:55pm

Dear @Philippe, what are your suggestions for me to write real C++ code? I mean what is the fastest and straightforward way to learn that? Is there any tutorial or valuable book or whatever else?

Philippe Mori 5-Aug-15 14:28pm

Use Google with words like: C++ tutorial std vector. One link would be http://www.codeguru.com/cpp/cpp/cpp_mfc/stl/article.php/c4027/C-Tutorial-A-Beginners-Guide-to-stdvector-Part-1.htm

There are also hundrends of book on C++.

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Richard MacCutchan · Accepted Answer · 2015-08-05T01:48:00

Solution 2

Rather than trying to learn C++ by posting questions here, your time would really be better spent getting hold of a good book on the subject and working through it. Looking at this and the other question you posted, there seems to be a lack of understanding of some of the basics.

Posted 5-Aug-15 1:48am

Richard MacCutchan

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[no name] 5-Aug-15 22:10pm

It had to be said.

CPallini · Accepted Answer · 2015-08-04T22:59:00

You function should be declared this way

C++

int * func(int array[]);

Please note: you should either return a static array or a dynamically allocated (e.g. using new) one. The latter technique requires the caller to delete the array in order to prevent memory leaks.

sample code:

C++

 #include <iostream>
int *  func(int array[])
{
  //...
  static int b[]={1,2,3};
  return b;
}
//
int main()
{
  int a[] = {4,5,6};
  int * p = func(a);
  std::cout << p[2] << std::endl;
}

It is worth nothing such code is prone to errors, it's probably better using std::vector instead.

[update]
Here you are a C-like version

 #include <iostream>
 using namespace std;


void dump(int * x, int lx);
void pad(int * d, int ld, int *s, int ls);

int main()
{
	int a[] = {1,2,3};
	int b[] = {4,6,8,10,12};
 	// length of a and b
	int la = sizeof(a)/sizeof(a[0]);
	int lb = sizeof(b)/sizeof(b[0]);
	int lp = 0;

	int * p = NULL;

	if ( la > lb)
	{
		lp = la;
		p = new int[lp];
		pad(p, lp, b, lb);
	}
	else if (la < lb)
	{
		lp = lb;
		p = new int[lp];
		pad(p,  lp, a, la);
	}
	
	dump(a, la);
	dump(b, lb);
	dump(p, lp);
        if ( p ) delete [] p;
}


void dump(int * x, int lx)
{
	for (int n=0; n<lx; ++n) cout << x[n] << " ";
	cout << endl;
}

void pad(int * d, int ld, int *s, int ls)
{
	int n;
	for (n=0; n<(ld-ls); ++n)
		d[n] = -1;
	
	for ( ;n<ld;++n)
		d[n] = s[n-ld+ls];
}

[/update]

[update 2]
More similar to C++ (you need a modern compiler)

C++

#include <iostream>
 #include <vector>

using namespace std;

void dump( vector<int> v );

int main()
{
    vector <int> a{1,2,3};
    vector <int> b{4,6,8,10,12};
    vector <int> p;

    if ( a.size() > b.size())
    {
        p.insert(p.end(), a.size()-b.size(),-1);
        p.insert(p.end(), b.begin(), b.end());
    }
    else if (a.size() < b.size())
    {
        p.insert(p.end(), b.size()-a.size(), -1);
        p.insert(p.end(),a.begin(), a.end());
    }

    dump(a);
    dump(b);
    dump(p);

}

void dump( vector<int> v )
{
    for (auto x : v)
        cout << x << " ";
    cout << endl;
}

[/update2]