我需要帮助创建一个可以搜索数组的函数

Question

Here is the question:

• Create a function that returns the product of two numbers between 1 and 9 by looking up the product in the array.
• Example: if the user enters 9 and 2 the program will look up the answer in the two dimensional array and display 18.

I have the table made I just don't know how to make a function that can search it.

#include <string> 
#include <iostream>
#include <iomanip>  
using namespace std;

int main()
{
    const int numRows = 10;
    const int numCols = 10;

    int product[numRows][numCols] = { 0 };

    for (int row = 0; row < numRows; ++row)
        for (int col = 0; col < numCols; ++col)
            product[row][col] = row * col;

    for (int row = 1; row < numRows; ++row)
    {
        for (int col = 1; col < numCols; ++col)
            cout << product[row][col] << "\t";
        cout << '\n';
    }

    return 0;
}

Answer 1

The idea behind generating the array is that all multiplication possibilities are stored in a table for easy lookup. There is no need to search all you need to do is lookup the value at the index like so:

int result = product[9][2];

The order of indicies doesn't matter either since 2*9 is the same as 9*2.

Answer 2

I would suggest you to read functions from here or any other good source you find.

Make a function with any name as follow and pass the two values and the 2D Array and use this simple way to extract the value

int productvalue(int a,int b, int product[][10])
{
    return product[a][b];
}

Complete Code:

#include <string> 
#include <iostream>
#include <iomanip>  
using namespace std;

int productvalue(int a,int b, int product[][10])
{
    return product[a][b];
}
int main()
{
    const int numRows = 10;
    const int numCols = 10;

    int product[numRows][numCols] = { 0 };

    for (int row = 0; row < numRows; ++row)
        for (int col = 0; col < numCols; ++col)
            product[row][col] = row * col;

    for (int row = 1; row < numRows; ++row)
    {
        for (int col = 1; col < numCols; ++col)
            cout << product[row][col] << "\t";
        cout << '\n';
    }
    int a,b;
    cin>>a>>b;
    //Example Call to the function
    int x = productvalue(a,b,product);
    cout<<x<<endl;
    return 0;
}