// Reminder

#include <iostream>

using namespace std;




int main(){

    int a[5][5],b[5][5],c[5][5],m,n,p,q,i,j,k;

    cout<<"Enter rows and columns of your first matrix: ";

    cin>>m>>n;

    cout<<"Enter rows and columns of your second matrix: ";

    cin>>p>>q;

    if(n==p){

        cout << "\nEnter your first matrix:\n";

        for (i=0; i<m; ++i);

        for (j=0; j<n; ++j);

        cin>>a[i][j];

        cout<<"\nEnter your second matrix:\n";

        for (i=0; i<p; ++i);

        for (j=0; j<q; ++j);

        cin >> b[i][j];

        cout << "\nThe new matrix is: \n";

        for (i=0; i<m; ++i){

            for(j=0; j<q; ++j)

                c[i][j]=0;

            for(k=0; k<n; ++k);

                c[i][j] = c[i][j] + (a[i][k]*b[k][j]);

            cout<<c[i][j]<<"\t";

        }

        cout<<"\n";

    }

else

    cout<<"\nMatrix multiplication can't be done";

return 0;

# Regular Expressions

Identifiers:
\d Any number 
\D Anything but a number
\s Space
\S Anything but a space
\w Any character
\W Anything but a character
. Any character except for a new line
\b Whitespace around words
\. A period

Modifiers:
{1,3} We are expecting 1-3
+ Match 1 or more
? Match 0 or 1
* Match 0 or more
$ Match the end of a string
^ Match the beginning of a string
| Either or E.g. \d{1-3}|\w {5-6}
[] Range or "variance" [A-Z] or [A-Za-z] [1-5a-qA-Z]
{x} Expecting "x" amount

White Space Characters:
\n New line
\t Tab
\s Space
\f Form
\e Escape
\r Return

DON'T FORGET! . + * ? [ ] $ ^ ( ) { } | \