CODEWITHSUNDEEP
visual-c++
mofodox
mofodox

Reputation: 51

How do I multiply 2 arrays in C++?

I am having trouble in multiplying 2 arrays.

Firstly, I want to have the user to input 7 int and store it in the first array.

Second array will be a const[] == {2765432};

The question is how do I multiply each of the element in both array

(i.e.) If the user input = 6192354, this will store first in an array then I want it to multiply with the second array. So it will be

6 * 2.. 1 * 7.. 9 * 6.. etc..

Upvotes: 3

Views: 24883

Answers (4)

paxdiablo
paxdiablo

Reputation: 881313

First off, {2765432} is not a seven-element array. It is a one-element array holding the single integer 2765432 but you seem to be after the seven-element variety.

To get that array of one-digit values, you need something like:

int second[] = {2,7,6,5,4,3,2};

Then, assuming you've read your user values into another seven-element array, it's as simple as:

for (int i = 0; i < 7; i++)
    result[i] = user[i] * second[i];

For example, this program:

#include <iostream>

int main() {
    int i, user[7], second[] = {2,7,6,5,4,3,2}, result[7];

    for (i = 0; i < 7; i++) {
        std::cout << "Enter value #" << (i + 1) << ": ";
        std::cin >> user[i];
    }

    for (i = 0; i < 7; i++) {
        result[i] = user[i] * second[i];
    }

    for (i = 0; i < 7; i++) {
        std::cout << user[i] << " * " << second[i] << " = " << result[i] << '\n';
    }

    return 0;
}

produces the following transcript when run:

Enter value #1: 1
Enter value #2: 3
Enter value #3: 2
Enter value #4: 8
Enter value #5: 4
Enter value #6: 7
Enter value #7: 4
1 * 2 = 2
3 * 7 = 21
2 * 6 = 12
8 * 5 = 40
4 * 4 = 16
7 * 3 = 21
4 * 2 = 8

If you find yourself needing to input one number and have it split up into an array of seven digits, you can start with this:

#include <iostream>

int main() {
    int i, val, user[7], second[] = {2,7,6,5,4,3,2}, result[7];

    std::cout << "Enter a seven-digit value: ";
    std::cin >> val;
    for (i = 6; i >= 0; i--) {
        user[i] = val % 10;
        val /= 10;
    }

    for (i = 0; i < 7; i++) {
        result[i] = user[i] * second[i];
    }

    for (i = 0; i < 7; i++) {
        std::cout << user[i] << " * " << second[i] << " = " << result[i] << '\n';
    }

    return 0;
}

It uses modulo and division to extract the digits one at a time into the user array, after which you're in the same situation as had you input the digits directly into the array.

Upvotes: 3

Rasim
Rasim

Reputation: 1296

Try to use std::transform. In the following manner:

#include <algorithm>
#include <functional>

...

std::transform(user, user + 7*sizeof(user[0]), second, result, std::multiplies<int>());

Upvotes: 2

maru
maru

Reputation: 81

Assuming both arrays have the same size, then the code below should work. Otherwise, a different logic would be needed.

for(int i = 0; i < 7; i++)
{
  int temp = answer[i] * const[i];
}

Upvotes: 0

rajansoft1
rajansoft1

Reputation: 1356

for(int i =0;i< A.length;i++)
{
    A[i] = A[i] * B[i];
}

=

Upvotes: 0

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