C++ How to Reduce the Number of "cout" to 6

Question

I want to reduce the number of "cout"s used in this program..So far I have 9 "cout"s in my program... First I had 11 "cout"s,but I could reduced to 9 by placing them inside a method. But still the over 6..

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

static void Endline(){
     cout << endl;
}

void printHeader(int start, int end) {
     cout << setw(4) << " ";
     for (int firstrow = start; firstrow <= end; firstrow++) {
        cout << setw(3) << firstrow << " ";
     }
     // cout << endl;
     Endline();

     // Second line, lead space then proper number of dashes
     cout << setw(4) << " ";
     for (int secondrow = start; secondrow <= end; secondrow++) {
        cout << "****";
     }
     //cout << endl;
     Endline();
}

int main() {
     int start;
     int end;

     // Collect start and end of listing
     cout << "Enter a start index (integer): " << endl;
     cin >> start;

     cout << "Enter an end index (integer): " << endl;
     cin >> end;

     for (int i = start; i <= end; i++) {
        // Executes once to print header
        if (i == start) {
            printHeader(start, end);
        }

        // Now loop through columns
        for (int j = start; j <= end; j++) {
            // Once per row create first column heading
            if (j == start) {
                cout << setw(3)<<  i << "|";
            }

            // Multiply row and column
            cout << setw(3) << (i * j) << " ";
        }

        // End row
        //cout << endl;
        Endline();
      }

     return 0;
}

Answer 1

If you stream the whole table into a std::stringstream and cout the result, you could reduce the number of couts to 3:

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

void printHeader(stringstream& result, int start, int end) {
    result<< setw(4) << " ";
    for (int firstrow = start; firstrow <= end; firstrow++) {
        result<< setw(3) << firstrow << " ";
    }
    result<< endl;

    // Second line, lead space then proper number of dashes
    result << setw(4) << " ";
    for (int secondrow = start; secondrow <= end; secondrow++) {
        result << "****";
    }
    result << endl;
}

int main() {
    int start;
    int end;

    // Collect start and end of listing
    cout << "Enter a start index (integer): " << endl;
    cin >> start;

    cout << "Enter an end index (integer): " << endl;
    cin >> end;

    stringstream result;

    for (int i = start; i <= end; i++) {
        // Executes once to print header
        if (i == start) {
            printHeader(result, start, end);
        }

        // Now loop through columns
        for (int j = start; j <= end; j++) {
            // Once per row create first column heading
            if (j == start) {
                result<< setw(3)<<  i << "|";
            }

            // Multiply row and column
            result << setw(3) << (i * j) << " ";
        }

        // End row
        result<< endl;
    }
    cout << result.str();
    return 0;
}

But: Why do you actually want to reduce the couts? According to this question cout seems to run with good performance.

Answer 2

What you want to do is reduce the amount of repetition in your code. This is something you always want to do when you program.

So, everytime you see two blocks of code that look alike (sometime bescause they come from a copy-paste), you should search for a way to write them as one function.

 cout << setw(3)<<  i << "|";

and

cout << setw(3) << (i * j) << " ";

and

cout << setw(3) << firstrow << " ";

are nearly the same. You can write them as a function taking as parameter the number to print, and the end character.

Similarly,

 cout << setw(4) << " ";

appears twice,

and

 cout << "Enter a start index (integer): " << endl;

appears twice also. You can wrap both in a function that you will call twice, like you did for the endl character.

You can thus remove 4 couts, this is enough right?