• Now declare a second string variable called word2.
• Next, write a cout statement welcoming your user to the program and letting them know that this program will alphabetize two words.

• Run your program to make sure it is giving you the output you expected.
• Let's prompt the user for the first word and store the result as word1.

• Do the same for the second word.
• Now, let's create an if-else statement to determine the ordering of the two words. And, then output the result to our user. The if-else statement will need to use string comparison as discussed above.

• The code that you have written could be a useful part of a larger program. 
  
• Both partners should submit to Canvas when finished.

Making Decisions Continued

• Sometimes, you will need to make a decision in our code that involves more than 2 possible outcomes.
• In this case we will use nested if statements.
• These nested if statements will follow this format:

Nesting in the else Clause

• When nesting if statements in the else clause, the computer can make only one selection
• As soon as a condition is found to be true, the rest of the selections are ignored
• The following code shows an example of a nested else if statement
• For example:

  if (guess < 7)
  {
      cout << "Your guess is too low.\n";
  }
  else if (guess > 7)
  {
      cout << "Your guess is too high.\n";
  }
  else
  {
      cout << "*** Correct! ***\n";
  }
  

• The trick in understanding this type of logic is to remember:
  • You start at the top
  • The computer makes only one selection
  • Once the selection is made and processes, the computer skips the rest of the options

Example Showing a Nested else if Statement

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#include <iostream>
using namespace std;

int main() {
    int guess = 0;
    cout << "I'm thinking of a number between"
         << " 1 and 10.\nCan you guess it?\n\n"
         << "Enter your guess: ";
    cin >> guess;

    if (guess < 7) {
        cout << "Your guess is too low.\n";
    } else if (guess > 7) {
        cout << "Your guess is too high.\n";
    } else {
        cout << "*** Correct! ***\n";
    }

    return 0;
}

Programming Style: Indentation of if-else-if Statements

• Note the alignment of the nested statements below:

  if (guess < 7)
  {
      cout << "Your guess is too low.\n";
  }
  else
  {
      if (guess > 7)
      {
          cout << "Your guess is too high.\n";
      }
      else
      {
          cout << "*** Correct! ***\n";
      }
  }
  

• The above style is WRONG
• Instead, we use:

  if (guess < 7)
  {
      cout << "Your guess is too low.\n";
  }
  else if (guess > 7)
  {
      cout << "Your guess is too high.\n";
  }
  else
  {
      cout << "*** Correct! ***\n";
  }
  

• This shows more clearly that we are making a single choice among multiple alternatives
• Also, it prevents indentations from cascading to the right as we add more selections

Multiple Alternatives

• By using collections of if-else statements, a program can distinguish between multiple alternatives

Choosing Between Alternatives

• This program has five alternatives to choose from:
  1. "penny"
  2. "nickel"
  3. "dime"
  4. "quarter"
  5. erroneous input
• Note that the order that the alternatives are checked is unimportant
• We can follow the alternatives in the flowchart shown below

Flowchart of Multiple Alternative for Converting Coins to Values

• For example, consider the following example where a user enters the name of a coin, and the program displays the value:
  

  Program Converting Coin Names to Values

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  #include <iostream> using namespace std; int main() { cout << "Enter coin name: "; string name; cin >> name; double value = 0; if (name == "penny") { value = 0.01; } else if (name == "nickel") { value = 0.05; } else if (name == "dime") { value = 0.10; } else if (name == "quarter") { value = 0.25; } else { cout << name << " is not a valid coin name\n"; } cout << "Value = " << value << "\n"; return 0; }

Activity 8.2: Grades (10 pts)

We want to write a program to calculate a student's letter grade according to the following table:

Numerical Grade	Letter Grade
greater than or equal to 90	A
less than 90 but greater than or equal to 80	B
less than 80 but greater than or equal to 70	C
less than 70 but greater than or equal to 60	D
less than 60	F

• Find a partner for pair programming.
  
• Open a new project in Eclipse called Grader with a file named grader.cpp. Change the comments to include your name, your partner's name and your section info.

• Compile and run your modified program to make sure you made the changes correctly. When you run the program, the output should look like:

  Enter a score: 80
  B
  

  Run your program a few times with different score to verify that any score displays the correct letter grade.

• When finished, both partners should upload the program to Canvas.

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#include <iostream>
using namespace std;

int main() {
    cout << "Enter a magnitude on the Richter scale: ";
    double richter;
    cin >> richter;

    if (richter >= 8.0) {
        cout << "Most structures fall\n";
    } else if (richter >= 7.0) {
        cout << "Many buildings destroyed\n";
    } else if (richter >= 6.0) {
        cout << "Many buildings considerably damaged, "
             << "some collapse\n";
    } else if (richter >= 4.5) {
        cout << "Damage to poorly constructed buildings\n";
    } else if (richter >= 3.5) {
        cout << "Felt by many people, no destruction\n";
    } else if (richter >= 0) {
        cout << "Generally not felt by people\n";
    } else {
        cout << "Negative numbers are not valid\n";
    }

    return 0;
}

• Find a partner and answer the questions from today's learning objectives