Implementing a Solution

• The next step in the programming process is to create a solution or program.
• I will do that now.
  • I will use this to introduce the process.
  • I expect you to understand the process and the tools.
  • I do not expect you to understand programming.
  • But I want you to see what we do before we go into further details.
• A program is a sequence of instructions to be performed by a computer. (blue box)
  • Note the similarity and difference from the definition of an algorithm.
  • At this stage, I think of an algorithm as an outline for a program.
• A program is written in a programming language
  • A set of rules, symbols, and special words used to construct a computer program. (blue box)
  • We will study the programming language c++
    • There are many others, but this is our choice.
  • Tiobe Index for Programming Languages
• The first thing we need is a text editor
  • A text editor allows us to enter text into a file.
  • I will use two
    • On windows I will use notepad++
    • On Linux I will use vi.
  • We will talk more about these next time, but you probably want notepad++ installed on your windows computer.
• For this class, we use one of our lab computers for the "standard".
  • For this class it is cslab103.cs.edinboro.edu
  • For the program to work, it must work on this computer.
  • We will discuss this later as well.
  • We will discuss accounts on this computer as well.
• If you work on windows, you will want a way to transfer data from your windows machine to cslab103.
  • For this I use winscp
  • You will want this installed on your windows computer if you plan to work from there.
• Finally you will need a way to log in to a remote computer
  • From windows I use putty
  • You will want this installed on your windows computer if you plan to work from there.
  • A local guide for putty is here
• The compiler we use is g++ on cslab103
  • This is a program that translates a high-level language into machine code. (book definition)
  • It will produce an object program or executable.
  • Or it will produce syntax errors
  • An overview of the compiling is here
• An overview of using these tools is here.
• Writing the code
  • I don't expect you to fully understand this, but watch the process.
  • There are some standard C++ things you do in every program.

    • #include <iostream>
      #include <iomanip>
      
      using namespace std;
      
      int main() {
          return 0;
      } 

  • For this program, I am going to use some constants
    • These represent values that are set, but could change in the future.
    • I need four of them

    • using namespace std;
      
      const float ADULT_TICKET_PRICE = 8.00;
      const float OTHER_TICKET_PRICE = 6.50;
      
      int main();
               

  • I need some variables
    • These are values that change each time I run the program.
    • Two are to hold the number of adults and others.
    • Five are to hold the results of the computations.

    • int adults = 0,
          others = 0;
      
      float adultCost = 0,
            otherCost = 0,
            totalTicketCost  = 0;
           

  • The first step in the algorithm was to get the number of adults and others.
    • We do this with cout and cin statements.

    • cout << "Enter the number of adults: ";
      cin >> adults;
      cout << endl;
      
      cout << "Enter the number of others: ";
      cin >> others;
      cout << endl; 

  • The next step was to compute the ticket costs.

    • adultCost = adults * ADULT_TICKET_PRICE;
      otherCost = others * OTHER_TICKET_PRICE;
      totalTicketCost = adultCost + otherCost; 

  • Finally, print out the results.

    • cout << fixed << setprecision(2);
      
      cout << "For " << adults << " adults and "
           << " others the price will be:" << endl;
      cout << "\tAdult Tickets\t$" << adultCost << endl;
      cout << "\tOther Tickets\t$" << otherCost << endl;
      cout << endl;
      cout << "\tTotal Cost\t$" << totalTicketCost << endl;
              

    • The full program is here
  • Compile the code
    • I named the source code file prog.cpp
    • I will compile this with the following command (in putty)

      g++ -o prog prog.cpp 

    • If successful, this will produce the executable prog
    • If not, it will produce at least one syntax error
    • 
      • In that case, I need to fix it and recompile.
      • NOTE: always fix the FIRST syntax error the compiler identifies.
        • This will be at the top of the list of errors.
  • Finally I can run the program.
    • 
  • At this point I should
    • Test it with the default input.
    • Test it with several other cases.
      • 1 adult no others. ($8 total)
      • no adult 1 others. ($6.5 total)