From c1b6ffe70bd281c6c230fd63fabcaac2aff47514 Mon Sep 17 00:00:00 2001
From: Fuwn <contact@fuwn.me>
Date: Sun, 7 Apr 2024 23:18:32 -0700
Subject: feat: initial commit

---
 chapter2/demo1.cxx | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 chapter2/demo1.cxx

(limited to 'chapter2/demo1.cxx')

diff --git a/chapter2/demo1.cxx b/chapter2/demo1.cxx
new file mode 100644
index 0000000..4c8bcca
--- /dev/null
+++ b/chapter2/demo1.cxx
@@ -0,0 +1,79 @@
+// FILE: demo1.cxx
+// This small demonstration shows how the throttle class is used.
+
+#include <iostream>         // Provides cout and cin
+#include <cstdlib>          // Provides EXIT_SUCCESS
+using namespace std;        // Allows all Standard Library items to be used
+class throttle
+{
+public:
+    // MODIFICATION MEMBER FUNCTIONS
+    void shut_off( );
+    void shift(int amount);
+    // CONSTANT MEMBER FUNCTIONS
+    double flow( ) const;
+    bool is_on( ) const;
+private:
+    int position;
+};
+
+int main( )
+{
+    throttle sample;
+    int user_input;
+    // Set the sample throttle to a position indicated by the user.
+    cout << "I have a throttle with 6 positions." << endl;
+    cout << "Where would you like to set the throttle? " << endl;
+    cout << "Please type a number from 0 to 6: ";
+    cin >> user_input;
+    sample.shut_off( );
+    sample.shift(user_input);
+    // Shift the throttle down to zero, printing the flow along the way.
+    while (sample.is_on( ))
+    {
+        cout << "The flow is now " << sample.flow( ) << endl;
+        sample.shift(-1);
+    }
+    cout << "The flow is now off" << endl;
+    return EXIT_SUCCESS;
+}
+
+void throttle::shut_off( )
+// Precondition: None.
+// Postcondition: The throttle has been turned off.
+{
+    position = 0;
+}
+
+double throttle::flow( ) const
+// Precondition: shut_off has been called at least once to initialize the
+// throttle.
+// Postcondition: The value returned is the current flow as a proportion of
+// the maximum flow.
+{
+    return position / 6.0;
+}
+
+void throttle::shift(int amount)
+// Precondition: shut_off has been called at least once to initialize the
+// throttle.
+// Postcondition: The throttle's position has been moved by amount (but not
+// below 0 or above 6).
+{
+    position += amount;
+
+    // Adjust the throttle if it went too high or too low
+    if (position < 0)
+        position = 0;
+    else if (position > 6)
+        position = 6;
+}
+
+bool throttle::is_on( ) const
+// Precondition: shut_off has been called at least once to initialize the
+// throttle.
+// Postcondition: If the throttle's flow is above 0 then the function
+// returns true; otherwise it returns false.
+{
+    return (flow( ) > 0);
+}
-- 
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