ALIGNER TEXTE CONSOLE

#include <iostream>
#include <sstream>
#include <iomanip>

namespace
{
  /*!
  ** Convert a string to a choosen type
  **
  ** @param t The dst type
  ** @param s The string to convert
  ** @param f The stream option
  **
  ** @return The dst type
  */
  template <class T>
  inline bool
  fromString(T& t,
	     const std::string& s,
	     std::ios_base& (*f)(std::ios_base&) = std::dec)
  {
    std::istringstream iss(s);

    return !(iss >> f >> t).fail();
  }

  /*!
  ** Compute the best width possible getting the max size of the max number
  **
  ** @param nb The number
  **
  ** @return Best width possible
  */
  inline int computeBestWidth(int nb)
  {
    std::ostringstream ss;

    ss << (nb * nb);

    return ss.str().length();
  }

  /*!
  ** Help below methods to draw a line
  **
  ** @param buff The buff to fill
  ** @param nb The max number
  ** @param line The current line
  ** @param width The width of each cell
  */
  inline void drawHelper(std::ostringstream& buff, int line, int nb, int width)
  {
    buff << std::setiosflags(std::ios::left);

    if (line == -1)
    {
      buff << std::setw(width) << '*';
      line = 1;
    }
    else
      buff << std::setw(width) << line;
    buff << "| ";
    for (int i = 1; i <= nb; ++i)
      buff << std::setw(width) << (i * line);
    buff << '\n';

    buff << std::resetiosflags(std::ios::left);
  }

  /*!
  ** Draw the header
  **
  ** @param buff The buff to fill
  ** @param nb The max number
  ** @param width The width of each cell
  */
  inline void drawHeader(std::ostringstream& buff, int nb, int width)
  {
    drawHelper(buff, -1, nb, width);
  }

  /*!
  ** Draw the line separator
  **
  ** @param buff The buff to fill
  ** @param nb The max number
  ** @param width The width of each cell
  */
  inline void drawLineSeparator(std::ostringstream& buff, int nb, int width)
  {
    buff << std::setfill('-') << std::setw(width * nb + width + 3)
	 << '\n'
	 << std::setfill(' ');
  }

  /*!
  ** Draw a line
  **
  ** @param buff The buff to fill
  ** @param nb The max number
  ** @param line The current line
  ** @param width The width of each cell
  */
  inline void drawLine(std::ostringstream& buff, int line, int nb, int width)
  {
    drawHelper(buff, line, nb, width);
  }

  /*!
  ** Draw all lines
  **
  ** @param buff The buff to fill
  ** @param nb The max number
  ** @param width The width of each cell
  */
  inline void drawBody(std::ostringstream& buff, int nb, int width)
  {
    for (int i = 1; i <= nb; ++i)
      drawLine(buff, i, nb, width);
  }

  /*!
  ** Draw a muliplication table
  **
  ** @param nb The max number
  */
  inline void displayComputeTable(int nb)
  {
    std::ostringstream buff;
    const int width = computeBestWidth(nb) + 1;

    drawHeader(buff, nb, width);
    drawLineSeparator(buff, nb, width);
    drawBody(buff, nb, width);

    std::cout << buff.str() << std::endl;
  }
}

/*!
** Given a valid number, this program draw a multiplication table
**
** @param argc Number of arguments
** @param argv List of arguments
**
** @return 1 if too few arguments, 2 if invalid argument, 0 else
*/
int main(int argc, char** argv)
{
  if (argc <= 1)
  {
    std::cerr << "Usage: " << argv[0] << " number" << std::endl;
    return 1;
  }

  int nb = 0;
  if (!fromString<int>(nb, argv[1]) || nb < 1)
  {
    std::cerr << "Invalid number: " << argv[1] << std::endl;
    return 2;
  }

  displayComputeTable(nb);

  return 0;
}