how to sum up two arrays together?

[Bleedz129]

for example if we have array1[5]= {1,2,3,4,5}
and array2[5]={2,3,4,0,7)

how do you sum them up as 12345 + 23407 . And when i say sum I mean normal mathematical sum.

here is my code to get an idea of what i am doing

int main ()
{
	string str1;
	string str2;
	int i, j;
	int size1, size2;
	int Num1[21];
	int Num2[21];
	

	cout <<" enter your first number: " << endl;
	cin >> str1;
	cout << endl;
	cout << str1 << " is your first number" << endl;
	
	cout << "enter the second number: " << endl;
	cin >> str2;
	cout << endl;
	cout << str2 << " is your second number" << endl;

	size1=str1.size();
	size2=str2.size();



	for(j=0;j<=size1;j++)

	{
		for (i=19; i>=0; i--)
		Num1[i]= str1.at(j);
	}
	
	for(j=0;j<=size2;j++)

	{
		for (i=19; i>=0; i--)
		Num2[i]= str2.at(j);
	}



}

[Smac89]

http://www.cplusplus.com/forum/general/100823/#msg542146

Simply arithmetic

If you have any questions about the code, I can help

[andywestken]

As Smac89 said, it's "simply arithmatic".

You just get the code to do what you do manually: add the units, add the tens, ... with carrying, etc.

Andy

PS You might want to consider

array1[5]= {9,8,7,6,5};
array2[4]= {4,3,2,1);

answer[6] = {1,0,3,0,8,6}

as your first test case, instead? Rather than

array1[5]= {1,2,3,4,5}
array2[5]= {2,3,4,0,7)

answer[5] = {3,5,7,5,2}

so you handle different length numbers correctly.

[ajh32]

Here's a neat way to sum two int arrays together:

#include <cstdlib>
#include <iostream>
#include <sstream>

class num
{
public:
	num()
		: number(0), result(NULL)
	{
	}

	num(int* numbers, unsigned size)
		: number(0), result(NULL)
	{
		std::stringstream ss;
		for (unsigned n=0; n < size; ++n)
			ss << numbers[n];
		ss >> number;
	}

	~num()
	{
		delete result;
	}

	num& operator+(const num& rhs)
	{
		if (result)
			delete result;
		result = new num();
		result->number = this->number + rhs.number;
		return *result;
	}

	friend std::ostream& operator<<(std::ostream& os, const num& n)
	{
		os << n.number;
		return os;
	}

private:
	int number;
	num* result;
};

int main(int argc, char* argv[])
{
	int a1[] = {9,8,7,6,5};
	int a2[] = {4,3,2,1};
	num a(a1, sizeof(a1)/sizeof(int)), b(a2, sizeof(a2)/sizeof(int));
	num result = a + b;
	std::cout << a << '+' << b << '=' << result << std::endl;

	return 0;
}

HTH

[JLBorges]

> for example if we have array1[5]= {1,2,3,4,5}
> and array2[5]={2,3,4,0,7)
> how do you sum them up as 12345 + 23407 .
> And when i say sum I mean normal mathematical sum.

#include <iostream>
#include <cassert>

int main()
{
    constexpr int N = 5 ;
    constexpr int a[N] = { 1, 2, 3, 4, 5 } ;
    constexpr int b[N] = { 2, 9, 8, 0, 7 } ;

    const auto isdigit = [] ( int v ) { return v >= 0 && v < 10 ; } ;
    int sum = 0 ;
    for( int i = 0 ; i < N ; ++i )
    {
        assert( isdigit( a[i] ) && isdigit( b[i] ) ) ;
        sum *= 10 ;
        sum += a[i] + b[i] ;
    }
    std::cout << sum << '\n' ;
}

http://ideone.com/J4qEc9